Portable spirometer

ABSTRACT

The invention relates to a spirometer (1) comprising a MEMS-based thermal fluid flow sensor (13, 13.1, 13.2) for generating a signal in response to a fluid flow generated during inhalation or exhalation; and a microcontroller (14) for calculating the fluid flow from the signal generated by the flow sensor (13, 13.1, 13.2). The spirometer (1) may be connected to other devices, such as a smartphone or a personal computer or any other computing unit which is adapted to collect, store, analyse, exchange and/or display data. The invention further describes the use of the spirometer (1) in measuring a user&#39;s lung performance and/or monitoring it over time. Furthermore, the spirometer (1) may be provided in a system together with an air quality measurement device for determining the air quality at a location of interest; and a computing unit for collecting, analysing and correlating the user&#39;s lung performance data obtained from the spirometer (1) with the air quality data, and optionally geolocalisation data of said location.

BACKGROUND OF THE INVENTION

The invention is related to a portable spirometry device, or spirometer,as well as a method for determining lung function parameters using saiddevice.

Spirometry is one of the most common tests used for determining, orevaluating, pulmonary function in terms of lung function parametersrelating to the amount (volume) and/or speed (flow, or flow rate) of airthat can be inhaled and exhaled, either forcedly or under normalbreathing. The primary signals measured in spirometry may be volumeand/or flow. Results are provided both as raw data (litres, litres persecond) and as percent predicted, i.e. in relation to predicted valuesfor patients of similar parameters such as height, age, sex, weight andsometimes ethnicity. Since multiple publications of predicted values areavailable, the interpretation of the results may vary slightly, butgenerally speaking, results close to 100% predicted are the most normal,and results 80% are usually also considered normal. Commonly, theresults are further displayed as graphs, so called spirograms orpneumotachographs, showing a volume-time curve (volume in litres on theY-axis and time in seconds on the X-axis) and/or a flow-volume loop(depicting the rate of airflow on the Y-axis and the total volumeinhaled or exhaled on the X-axis).

Spirometry is an important tool in the assessment of various obstructiveor restrictive lung conditions such as asthma, chronic obstructivepulmonary disease (COPD), bronchitis, emphysema, pulmonary fibrosis(PF), and also cystic fibrosis (CF), because the tests performed withthe so-called spirometer (i.e. a device, or apparatus, for measuringventilation, the movement of air into and out of the lungs) are able toidentify abnormal ventilation patterns, namely obstructive andrestrictive patterns.

Lung function parameters that can be determined using spirometry and/ora spirometer include e.g.: vital capacity (VC; volume exhaled afterdeepest inhalation); forced vital capacity (FVC; determination of thevital capacity from a maximally forced expiratory effort); slow vitalcapacity (SVC); forced expiratory flow (FEF), peak expiratory flow (PEF;highest forced expiratory flow, measured with a peak flow meter); forcedexpiratory volume (FEV_(X); volume of air exhaled under forcedconditions in the first X seconds; e.g. FEV₁=volume force-exhaled after1 second); forced expiratory time (FET), inspiratory vital capacity(IVC; maximum volume inhaled after maximum expiration); forcedinspiratory vital capacity (FIVC); residual volume (RV; volume of airremaining in the lungs after maximum exhalation; sometimes expressed inpercent based on total lung capacity); total lung capacity (TLC; volumein lungs after maximum inhalation; sum of VC and RV); tidal volume (TV;volume of air moved into or out of the lungs during quiet breathing);inspiratory or expiratory reserve volume (IRV and ERV; maximal volumethat can be inhaled or respectively exhaled from the end-inspiratorylevel or respectively end-expiratory level); inspiratory capacity (IC;sum of IRV and TV); functional residual capacity (FRC; volume in thelungs at the end-expiratory position); extrapolated volume (EVOL),estimated lung age (ELA); maximal voluntary ventilation (MVV; alsocalled maximum breathing capacity); and others.

As mentioned, the test procedures are performed using a spirometer.Various types of these devices are known, from simple mechanicallyoperating to fully electronic ones; said devices using a number ofdifferent measurement principles such as water gauges, ‘windmill’-typerotors (also called turbines) or pressure transducers. Most conventionalspirometers evaluate the fluid flow by measuring either a pressuredifference before and after a membrane, capillaries or other forms offlow restriction with a known resistance (e.g. using a differentialpressure sensor), or by the rotations of a turbine. In the past, effortsincreased to render the devices portable and/or handheld, in order toobtain a more detailed and concise monitoring of e.g. therapy efficacyby allowing the patients, or users, to perform spirometry measurementsby themselves; thereby obviating the need to visit a doctor's office ora hospital. Some of these portable devices are even aimed at beingconnectable to e.g. a patient's smartphone.

For instance, the Vitalograph's asma-1 device is a small, handheld,AAA-battery-powered device to measure and store PEF and FEV₁ values. Thedevice is equipped with a rotatable turbine and disposable mouthpiecesand can be connected via USB or Bluetooth to a mobile phone, PDA, PC orhome hub. Unfortunately, the device can store only a limited number ofmeasurements (up to 600) and no parameters other than PEF and FEV₁ canbe measured. In other words, no full spirometry as defined by thespirometry standards of the American Thoracic Society (ATS) and theEuropean Respiratory Society can be performed by the device; see“Standardisation of spirometry”; Eur Respir J 2005; 26: 319-338 (forinstance, these standards define 24 ATS waveforms that the spirometermust correctly identify, some of these generated at higher temperatureof 37° C. and high humidity, and additionally, the total resistance toairflow at 0-14.0 L/s must be <0.15 kPa/(L/s)).

Baltimore based company Respi is working on an iPhone® spirometer and arespective respiratory data platform. Respi's prototypical 3D printedspirometer aims at using the smartphone (Apple's Lightning Connector foriPhone® 5s) as a power source and the smartphone's internal sensors toensure proper body posture during the measurement. The device isequipped with a rotating wing and a laser sensor taking several thousandmeasurements per second. The collected data are said to be adjustedbased on environmental conditions such as pressure and temperature, andany gathered information on a cloud which allows constant patientmonitoring, individual spirometry assessment, personalized real-timeconsultation and big population analytics. Disposable mouthpieces fromMIR (Medical International Research) are used to ensure hygiene. Whilethe spirometer is capable of full spirometry (e.g. not just peak flowmeasurements), it is also associated with various drawbacks; e.g. thesmartphone application (or ‘app’) is currently missing the option tocoach a patient through a breathing manoeuver for 6 seconds.Furthermore, dedicated adapters and/or wireless communication mechanismswould be required to work with other types of smartphones than theiPhone® (Respi suggests Bluetooth 4.0).

Introduced in 2012, SpiroSmart is a low-cost mobile phone applicationthat performs spirometry (namely FEV₁, FVC, PEF, and FEV₁%) using thebuilt-in microphone in the smartphone (iPhone®). The app is intended fornon-chronic disease management, and monitoring air quality effectsand/or allergic reactions. The app records the user's exhalation anduploads the audio data generated with the microphone to a server. Theserver then calculates the expiratory flow rate using a physiologicalmodel of the vocal tract and a model of the reverberation of soundaround the user's head, and final results are then sent back to thesmartphone app. However, the system and app are associated with a numberof disadvantages. According to the inventors, usability and trainingchallenges exist and patients with severely low lung function may notgenerate any sound. Algorithms created from audio data collected on aspecific smartphone model may not be generalisable to other models orbrands. Further, the user needs to ensure that he always holds thesmartphone at the same position (e.g. an arms length from the mouth) andat the correct angle; and that he opens his mouth wide enough.SpiroSmart—same as a majority of spirometry tests relying on soundsignals—can only be used in quiet settings, and in contrast to fullspirometry as performed e.g. in hospital settings, the inhalation whichis typically (almost) inaudible would not be recorded by the smartphone.And currently the smartphone app cannot calculate all features in realtime; especially the flow-volume loops requiring extensive computation,such that the analysis is done in the cloud (i.e. storage of digitaldata on one or multiple physical servers, typically owned and managed bya hosting company).

Alternatively to SpiroSmart, a call-in-service (SpiroCall) may be usedby users who do not own a smartphone. In that case, the standardtelephony voice channel is employed to transmit the sound of thespirometry effort. The tests can be performed either with or without theuse of a simple 3D-printed SpiroCall whistle which generates vortices asthe user exhales through it, changing its resonating pitch in proportionto the flow rate. SpiroCall combines multiple regression algorithms toprovide reliable lung function estimates despite the degraded audioquality over a voice communication channel. The server then computes thelung function parameters and the user receives a response via a textmessage on their phones.

A similar acoustics based and smart-phone connectable device isAirSonea®'s portable ‘digital stethoscope’ and its related smartphoneapp which records breath sounds to detect and measure wheeze, a typicalsound resulting from a narrowing of the airways and one of the primarysigns of asthma. The AirSonea® sensor is held at the trachea (windpipe)during 30 seconds of normal breathing. The app then records and analysesthe breathing sounds and returns a WheezeRATE™, a measurement of theextent of wheezing over the duration. The WheezeRATE™ history is storedin the smartphone and synced to the Cloud for review and sharing withe.g. healthcare professionals However, wheeze is not well validatedclinically for monitoring of asthma treatment (lack of clinicalguidelines in this field) and the device is not capable of measuringspirometric parameters.

Medical International Research's (MIR) offers a broad range of devicesfor measurements of respiratory parameters, some of them portable andsome connectable to mobile phones. For instance, the Smart One® deviceis a portable turbine flowmeter, optionally using MIR's customarydisposable FlowMIR® turbine and cardboard mouth piece. The device can beconnected via Bluetooth to a smartphone on which the respective SmartOne® app (available for iOS and Android) and the measured respiratorydata are stored. The device is capable of determining e.g. PEF and FEV₁;however, no full spirometry can be performed with the device.

MIR's Spirodoc® and Spirobank® II Smart devices are portable,pocket-sized, standalone (i.e. requiring no computer) turbine flowmeterdevices capable of performing full spirometry and storing up to 10.000spirometry tests. The Spirodoc® device comprises an approximatelypalm-sized main body with an LCD touchscreen display, an attachableflowmeter head housing a bi-directional digital turbine (e.g. thedisposable FlowMIR® turbine), and a temperature sensor for BTPSconversion of FVC measurements (i.e. vital capacity at maximally forcedexpiratory effort, expressed in litres at body temperature andambientpressure saturated with water vapour). The Spirobank® II Smartdevice differs mainly in that a keyboard is used instead of Spirodoc®'stouchscreen and in that the flowmeter head is permanently fixed.Alternatively to the keyboard, the Spirobank® II Smart device may alsobe operated via a tablet computer (iPad™). A smartphone connectivity isnot provided, though.

Both devices may optionally further comprise a fingertip pulse oximeterthat can be attached via cable to the main body. A built-in three-axismovement sensor is provided in the devices in order to correlate theoxygen saturation level (% SpO2) measured with the fingertip oximeter tothe user's physical activity. Data transmission, e.g. to a personalcomputer (PC) running the related WinspiroPRO® software—or for theSpirobank® Smart an iPad/iPad mini running the iOS-based MIR Spiro®app—may be achieved via Bluetooth or USB connection. Only when connectedto a PC or iPad, the respective software allows for real time spirometryand oximetry tests; i.e. real time curve display. Unfortunately, thisneed of e.g. a tablet computer or the like increases the costs for thesedevices.

A further portable, pocket size homecare spirometer in the product rangeof MIR is the Spirotel® which uses an attachable, reusablebi-directional digital turbine and a small touchscreen in a main-bodythat is connectable to a personal computer (PC) via a USB-cable orBluetooth; a software application (WinspiroPro Home Care) then extractsthe data and sends it to a server. Same as with the Spirodoc® andSpirobank® II Smart devices, the Spirotel® may optionally furthercomprise a fingertip pulse oximeter that can be attached via cable tothe main body, and a built-in three axis movement sensor to correlatethe measured oxygen saturation level (% SpO2) to the user's physicalactivity. While being portable itself, the Spirotel® device cannot beused as a standalone and is not connectable to smart phones, butrequires the use of a PC instead.

One common disadvantage of most of the above listed devices is the useof movable parts, namely the turbines or rotating wings, to measure gasflow. This necessitates regular external calibrations, e.g. annually orbiannually. Furthermore, a majority also lacks the option to measurespirometric parameters such as FEV₆, FRC, SVC, MVV or ERV.

A portable, battery operated device using a gas flow sensor withoutmovable parts is the SpiroTube mobile edition by Thor Laboratories, apulmonary function diagnostics and monitoring device with Bluetooth orUSB connection to a PC (storing the ThorSoft pulmonary diagnostics PCsoftware). Bluetooth and also WIFI connection is available as an optionto connect the SpiroTube to iPad/iPhone, Android smartphones, PDAdevices as well as any JAVA-ready mobile device. The SpiroTube uses theproprietary IDEGEN™ multipath measurement principle wherein the flowvolume measurement depends on the quantity and energy of gas molecules,measured using ultrasound and the Doppler Effect. The inner surface ofthe flow tube is continuous and free of any obstacles such that it canbe disinfected easily.

A further device without movable parts is the WING device by US-basedSparo Labs which can be cable-connected to a smartphone via theheadphone jack and which measures PEF (peak expiratory flow) and FEV₁(volume force-exhaled after 1 second). Measured data are synced to a‘cloud’ in encrypted form and can be analysed using a dedicatedsmartphone application. Unfortunately, no parameters other than PEF andFEV₁ can be measured (e.g. no forced vital capacity (FVC), forcedexpiratory flow at 25%-75% of FVC (FEF25-75), etc.). In other words, nofull spirometry as defined by the spirometry standards of the AmericanThoracic Society (ATS) and the European Respiratory Society can beperformed; similar to e.g. the asma-1 device described above. Also, theWING runs on the phone's battery (via the headphone jack), such that itis at risk to not measure data properly if the phone battery is low.

Alternatively, acceleration sensors (also called accelerometers orgyro-sensors) such as MEMS based thermal fluid flow sensors (MEMS;microelectromechanical systems) have also been suggested in the priorart for flow measurements in medical devices including ventilators,sleep apnoea devices, spirometers, etc.; for instance, by MEMSIC, one ofthe producers of these type of sensors. These MEMS based thermal fluidflow sensors use temperature sensors, such as thermocouples, and gasmolecules heated via a resistive heating element. When subjected toacceleration, the less dense molecules in the heated gas move in thedirection of acceleration and the cool and denser molecules move in theopposite direction, creating an acceleration proportional temperaturedifference measured by the temperature sensors. However, to the best ofthe inventor's knowledge, this conceptual idea of employing MEMS basedthermal fluid flow sensors for flow measurements in medical devices hasnever been translated into an existing, operable, functional spirometerbefore; i.e. up to the present invention, it was not clear whether theconcept could actually be put into practice and how exactly accurate andreproducible, or precise, spirometric flow measurements could beachieved.

It is an object of the present invention to provide an improved portablespirometer which overcomes the draw backs of prior art devices; e.g. adevice with higher measurement sensitivity that can be used withoutmedically trained staff and which is capable of performing fullspirometry, including measurements of main spirometry parameters such asFEV₁, FVC, PEF, and FEV₁% but also parameters such as FEV₆, FRC, SVC,MVV or ERV. This object is achieved by the subject matter of the presentinvention as set forth in the claims, namely by a portable spirometeremploying MEMS based thermal fluid flow sensors as a measurementprinciple. It was further an object of the present invention to providea portable spirometer with a MEMS based thermal fluid flow sensor, whichis optimized with regard to the flow properties inside the device inorder to enable accurate and reproducible, or precise, spirometric flowmeasurements.

SUMMARY OF THE INVENTION

In a first aspect, the invention provides a portable electronicspirometer comprising (a) a tubular mouthpiece and (b) a main body. Thetubular mouthpiece comprises a proximal opening for insertion into themouth of a user, a distal opening, and a main fluid channel extendingbetween these two openings. The mouthpiece further comprises a firstlateral opening and a second lateral opening positioned at alongitudinal distance to the first; as well as a flow restrictorpositioned in the main fluid channel between the first and the secondlateral opening. The main body comprises a first fluid openingconnectible with the first lateral opening of the mouthpiece, a secondfluid opening connectible with the second lateral opening of themouthpiece, and a bypass fluid channel extending between the first andthe second fluid opening. The main body further comprises a MEMS-basedthermal fluid flow sensor positioned at the bypass fluid channel forgenerating a signal in response to the fluid flow in the bypass fluidchannel; and a microcontroller connected with the fluid flow sensor forcalculating the fluid flow from the signal generated by the flow sensor.One embodiment of this spirometer is depicted e.g. in FIG. 2 .

The flow restrictor in this spirometer may exhibit a flow resistance, orimpedance, in the range from about 0.01 to about 0.2 kPa/(L/s),preferably from about 0.01 to about 0.15 kPa/(L/s), and more preferablyfrom about 0.01 to about 0.1 kPa/(L/s) at a fluid flow of 60 SLM to 900SLM (or SLPM; standard liter per minute); and/or it may be adapted orconfigured such as to cause a fluid flow in the bypass fluid channelwhich is from about 1:10 to about 1:200 of the fluid flow in the mainfluid channel, i.e. a the fluid flow in the bypass channel may rangefrom about 0.3 SLM to about 90 SLM. The flow restrictor may be aperforated disk having a cross-sectional orientation with respect to themain fluid channel, e.g. a perforated disk exhibiting from about 1 toabout 100 perforations, or from about 2 to about 100 perforations, orfrom about 4 to about 100 perforations, or from about 15 to about 100perforations (optionally circular, elliptic or polygonal in shape, orshaped as sectors of a circle or oval), and/or exhibiting a totalcombined area of all perforations ranging from about 26% to about 96%,or from about 39% to about 96%, or from about 26% to about 72%, of thecross-sectional area of the main fluid channel at the position of theperforated disk. For instance, the flow restrictor may be a perforateddisk with a total surface area of about 587 mm², comprising 55perforations which are shaped as regular hexagons and exhibit a‘perforated surface area’ of about 175 mm², or about 30% of the flowrestrictor's total surface area; or the flow restrictor may be aperforated disk with a total surface area of about 587 mm², comprising37 perforations of circular shape and a ‘perforated surface area’ ofabout 261 mm², or about 45% of the flow restrictor's total surface area.

The distance between said flow restrictor and the first lateral openingalong the longitudinal axis of the main fluid channel of the spirometermay be from about 5 mm to about 15 mm, preferably about 10 mm, e.g. 10.0mm; and the distance between the flow restrictor and the second lateralopening from about 25 mm to about 45 mm, preferably about 34 mm, e.g.34.2 mm.

The MEMS-based thermal fluid flow sensor of the spirometer may be abidirectional flow sensor, such as to allow e.g. for measurements duringboth inhalation and exhalation. The MEMS-based thermal fluid flow sensormay e.g. be a monolithic complementary metal-oxide-semiconductor (CMOS)flow sensor comprising a sensor chip, the chip comprising anencapsulated gas bubble, a microheater for heating the gas bubble, afirst plurality of thermopiles located on a first side of the gasbubble, and a second plurality of thermopiles located on a second sideof the gas bubble which is opposite to the first side. This type of flowsensor also acts as a temperature sensor for measuring the temperatureof the breath at the same time.

The spirometer may further comprise an acceleration sensor which isdifferent from the MEMS-based thermal fluid flow sensor, for instance a3-axis sensor with a sensitivity (So) of at least 973 counts/g±5% foreach of the three axes; typically, the sensitivity ranges between 973and 1075 counts/g; e.g. 1024 counts/g. Such acceleration sensors e.g.allow for correcting the calculated fluid flow. For instance, themicrocontroller of the spirometer may be programmed to calculate acorrected fluid flow from the signal generated by the flow sensor andfrom a signal generated by the acceleration sensor. Furthermore, thisacceleration sensor may also be employed—similar to the MEMS-basedthermal fluid flow sensor—for measuring the temperature of the breath.

The spirometer may further comprise a heart rate sensor, a blood oxygensaturation sensor, a temperature sensor for measuring the temperature ofthe environment, an atmospheric pressure sensor, and/or a moisturesensor. Each of these one or more sensors may be directly or indirectlyconnected with the microcontroller such that the microcontroller iscapable of receiving a signal from each of the one or more sensors.

The spirometer may further comprise a communication means, preferably awireless communication means, and more preferably a radio communicationmeans.

Furthermore, the spirometer may exhibit a mean energy consumption of thedevice during its operation which is not higher than 90 mA in total,preferably not higher than about 50 mA.

In a second aspect, the invention provides a method for measuring ahealth parameter of a human subject selected from a forced vitalcapacity (FVC), a forced expiratory volume (FEV), a peak expiratory flow(PEF), a forced expiratory flow (FEF), a maximum voluntary ventilation(MVV), a mean expiratory flow, a slow vital capacity (SVC), a functionalresidual capacity (FRC), an expiratory reserve volume (ERV), a maximumspeed of expiration, a forced inspiratory volume (FIV), a forcedinspiratory vital capacity (FIVC), a peak inspiratory flow (PIF), or anycombination of these, the method comprising a step of the human subjectperforming a breathing manoeuvre through the spirometer as describedabove.

In a third aspect, the invention provides a system comprising:

-   -   the portable electronic spirometer (1) according to the first        aspect of the invention, and    -   a first air quality measurement device comprising communication        means adapted for data exchange with the portable electronic        spirometer (1) and/or with a separate computing unit, and        equipped with one or more air quality sensors, preferably        selected from the group consisting of humidity sensors,        temperature sensors, atmospheric pressure sensors, MOS-type gas        sensors (metal-oxide-semiconductor), airborne-particles sensors,        pollen sensors, ozone (O₃) sensors, nitrogen dioxide (NO₂)        sensors, sulfur dioxide (SO₂) sensors and carbon monoxide (CO)        sensors, for determining determine the air quality at the        location of the first air quality measurement device, and        optionally    -   a separate computing unit adapted to collect and analyse at        least the data obtained from the spirometer (1) according to the        first aspect of the invention and from the first air quality        measurement device.

Using said system, the method according to the second aspect of theinvention may be complemented with additional data such as data relatedto the air quality (pollutants, ozone, pollen, etc.) and/or geolocationdata, thereby allowing to compare and/or correlate the health parameterof the human subject (such as FVC, FEV, PEF, FIV, FIVC, PIF, etc., asdescribed above) with these additional data.

In other words, a fourth aspect of the invention provides a methodwherein one or more health parameters of a human subject selected from aforced vital capacity (FVC), a forced expiratory volume (FEV), a peakexpiratory flow (PEF), a forced expiratory flow (FEF), a maximumvoluntary ventilation (MVV), a mean expiratory flow, a slow vitalcapacity (SVC), a functional residual capacity (FRC), an expiratoryreserve volume (ERV), a maximum speed of expiration, a forcedinspiratory volume (FIV), a forced inspiratory vital capacity (FIVC), apeak inspiratory flow (PIF), or any combination of these, are measuredby the human subject performing a breathing manoeuvre through thespirometer according to the first aspect of the invention; and whereinthe one or more health parameters are compared and/or correlated withair quality data, and optionally geolocalisation data, derived from thesystem according to the third aspect of the invention.

Further objects, aspects, useful embodiments, applications, beneficialeffects and advantages of the invention will become apparent on thebasis of the detailed description, the examples and claims below.

OVERVIEW OF REFERENCE NUMBERS

-   1 Spirometer-   2 Tubular mouthpiece-   2.1 Front end of mouthpiece-   3 Proximal opening-   4 Distal opening-   5 Main fluid channel-   6 First lateral opening-   7 Second lateral opening-   8 Flow restrictor-   8.1 Perforated disk-   8.2 Perforations-   8.3 Rib(s)-   8.4 Outer ring-   9 Main body-   10 First fluid opening-   11 Second fluid opening-   12 Bypass fluid channel-   13 MEMS-based thermal fluid flow sensor-   13.1 Bidirectional flow sensor-   13.2 Monolithic CMOS flow sensor-   14 Microcontroller-   15 Acceleration sensor-   15.1 3-axis sensor-   16 Heart rate sensor-   17 Blood oxygen saturation sensor-   18 Environmental temperature sensor-   19 Atmospheric pressure sensor-   20 Moisture sensor-   21 Radio communication means-   21.1 Bluetooth connectivity-   21.2 NFC means-   21.3 WLAN means-   22 Cable communication means-   22.1 USB communication means-   23 Optical signalling means-   23.1 Signalling LEDs-   24 Acoustical signalling means-   25 ON/OFF-button-   26 Battery-   27 Main board-   28 Breath temperature sensor

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A-C show one embodiment of the tubular mouthpiece (2) of thespirometer (1) in top view (A), side view (B) and in perspective view(C). The mouthpiece (2) comprises a proximal (3) and a distal opening(4) with a main fluid channel (5) extending therebetween, a first and asecond lateral opening (6 and 7) as well as a flow restrictor (8)positioned in the main fluid channel (5) perpendicular to the channel'slongitudinal axis the and between the two lateral openings (6 and 7). Inthe depicted embodiment, the flow restrictor (8) is a perforated disk(8.1) with 55 hexagonal perforations, as can be seen in more detail inFIG. 3A.

FIG. 2 shows a perspective crosssection of one embodiment of thespirometer (1). On top of the tubular mouthpiece (2) with the main fluidchannel (5), the flow restrictor (8), and the first and second lateralopening (6 and 7) sits a detachable main body (9) with a first and asecond fluid opening (10 and 11) and a bypass fluid channel (12)extending therebetween. A MEMS-based thermal fluid flow sensor (13,13.1, 13.2), which also acts as a breath temperature sensor (28), ispositioned at the top side, or upper side, of the bypass fluid channel(12). In the depicted version, the first and the second fluid opening(10 and 11) are connected to the first and second lateral opening (6 and7) of the tubular mouthpiece (2).

FIGS. 3A, 3B, 3C and 3D show crosssections of four embodiments of thespirometer (1) at the position of the flow restrictor (8), morespecifically at the position of a perforated disk (8.1) as employed inspecific embodiments of the spirometer (1), with either regularhexagonal perforations (8.2; FIG. 3A, here 55), or circular perforations(8.2; FIG. 3B, here 37), or perforations shaped as sectors of a circleor oval (8.2, FIG. 3C, here 6) dissected by straight ribs (8.3), orirregularly shaped perforations (8.2, FIG. 3D).

As can be seen in FIG. 3C, the depicted exemplary perforated disk (8.1)comprises an outer ring (8.4) whose larger outer diameter matches theinner diameter of the main fluid channel (5) of the spirometer (1) andwhose smaller inner diameter defines a central opening (here depicted asa circle); and a plurality of ribs (8.3) extending from said outer ring(8.4) towards the center of this central opening, and overlapping therein such a way that the circle is dissected across its complete diameterby the ribs (8.3). In other words, the ribs (8.3) contact the outer ring(8.4) of the perforated disk (8.1) at two points, thereby formingperforations shaped as sectors of a circle.

FIG. 3D shows an alternative perforated disk (8.1) with a single,irregularly shaped perforation (8.2) formed by an outer ring (8.4) and asingle rib (8.3) which dissects the central opening formed in/by theouter ring (8.4) only partially; i.e. the rib (8.3) contacts the outerring (8.4) only at one point, while the opposite end is free.

FIG. 4 shows the main board (27) of one embodiment of the spirometer (1)in top view as well as the positions of the sensors (13, 13.1, 13.2, 15,15.1, 18, 19, 20, 28), the micro-controller (14), the radiocommunication means (21, 21.1), the NFC means (21.2), the cablecommunication means (22, 22.1), and the optical signalling means (23,23.1).

FIG. 5 shows a further embodiment of the tubular mouthpiece (2) of thespirometer (1) in perspective view. The mouthpiece (2) comprises aproximal (3) and a distal opening (4) with a main fluid channel (5)extending therebetween, a first and a second lateral opening (6 and 7)as well as a flow restrictor (8) positioned in the main fluid channel(5) perpendicular to the channel's longitudinal axis the and between thetwo lateral openings (6 and 7). In the depicted embodiment, the flowrestrictor (8) is a perforated disk (8.2) with 6 perforations (8.2)which are shaped as sectors of a circle, with said circle beingdissected across its complete diameter by straight ribs (8.3), as can beseen in more detail in FIG. 3C.

DEFINITIONS

The following terms or expressions as used herein should normally beinterpreted as outlined in this section, unless defined otherwise by thedescription or unless the specific context indicates or requiresotherwise:

All technical terms as used herein shall be understood to have the samemeaning as is commonly understood by a person skilled in the relevanttechnical field.

The words ‘comprise’, ‘comprises’ and ‘comprising’ and similarexpressions are to be construed in an open and inclusive sense, as‘including, but not limited to’ in this description and in the claims.

The singular forms ‘a’, ‘an’ and ‘the’ should be understood as toinclude plural referents. In other words, all references to singularcharacteristics or limitations of the present disclosure shall includethe corresponding plural characteristic or limitation, and vice versa.The terms ‘a’, ‘an’ and ‘the’ hence have the same meaning as ‘at leastone’ or as ‘one or more’. For example, reference to ‘an ingredient’includes mixtures of ingredients, and the like.

The expressions, ‘one embodiment’, ‘an embodiment’, ‘a specificembodiment’ and the like mean that a particular feature, property orcharacteristic, or a particular group or combination of features,properties or characteristics, as referred to in combination with therespective expression, is present in at least one of the embodiments ofthe invention. These expressions, occurring in various places throughoutthis description, do not necessarily refer to the same embodiment.Moreover, the particular features, properties or characteristics may becombined in any suitable manner in one or more embodiments.

All percentages, parts and/or ratios in the context of numbers should beunderstood as relative to the total number of the respective items,unless otherwise specified, or indicated or required by the context.Furthermore, all percentages parts and/or ratios are intended to be byweight of the total weight; e.g. ‘%’ should be read as ‘wt.-%’, unlessotherwise specified, or indicated or required by the context.

‘Essentially’, ‘about’, ‘approximately’ (approx.), ‘circa’ (ca.) and thelike in connection with an attribute or value include the exactattribute or the precise value, as well as any attribute or valuetypically considered to fall within a normal range or variabilityaccepted in the technical field concerned.

‘Front’ as well as all similar terms designating a position, orientationor direction, such as ‘left’, ‘right’, ‘rear’ ‘back’, ‘top’, ‘bottom’,‘up’, ‘down’ and the like, should be understood with reference to theorientation of the spirometer or its components under normal operationalconditions. ‘Lateral’, or ‘laterally’, means away front the middle,centre, or centre axis of a device or device component.

The terms ‘sensor’ and ‘transducer’ are used synonymously herein, unlesswhere specified otherwise, and refer to means which are capable ofmeasuring a parameter (for instance, a force, a temperature or a sound)and transmitting a related signal to a data analysis unit, e.g. anelectric signal which can be received, read, stored and analysed by acomputer or a similar data analysis unit. In that regard, it should beunderstood that wordings such as ‘a signal obtained from a sensor . . .’ strictly speaking refers to the signal as transmitted to the computer,and thus not necessarily to the actual measured parameter, or measurand,such as a force which triggered the respective signal.

The term ‘spirometry’ or ‘full spirometry’ refers to the entirety ofmeasurements related to the breathing capacities, or pulmonary function,of the lungs of a breathing subject, both during inhalation orexhalation, as well as during forced or quiet breathing manoeuvres.These measurements are done both qualitatively as well asquantitatively. The term ‘spirometer’ as used herein thus refers todevices which are capable to perform these measurements. Examples of themost common parameters measured in (full) spirometry are vital capacity(VC), forced vital capacity (FVC), forced inspiratory vital capacity(FIVC), forced expiratory volume (FEV) at timed intervals in seconds(e.g. FEV₁=FEV in 1 second), forced expiratory flow (FEF), peakexpiratory flow (PEF; also called peak flow), forced expiratory time(FET) and maximal voluntary ventilation (MVV; also called maximumbreathing capacity). In other words, spirometry includes, orencompasses, peak flow measurements; therefore, it is understood thatthe spirometer according to the present invention may also be employedas a peak flow meter, while not being limited to this functionalityalone. The vice-versa case is not necessarily valid; i.e. a peak flowmeter is not a spirometer if limited to the functionality of measuringpeak flows. Likewise, while the ‘spirometers’ in the sense of thepresent invention could in theory be employed for so-called incentivespirometry (a technique in which a subject is instructed to repeatedlyinhale slowly and optionally hold its breath in order to inflate thelungs and keep the small airways open, e.g. after lung surgery or inbed-ridden patients), not every incentive spirometer can necessarilyperform the above described qualitative and quantitative measurements oflung function parameters, and hence does not necessarily qualify as a‘spirometer’ in the sense of the present invention, despite thesimilarity in names.

The term ‘portable’ as used herein refers to products, in particularspirometers, whose size and weight renders them suitable to be carriedcomfortably and for extended periods of time (such as the whole dayand/or on a daily basis) by human users of said product withoutadditional help; for instance, by simply holding it in one hand or byplacing it in the pockets of trousers or coats or in a handbag. Hence,terms such as pocket-sized and/or handheld are understood to besynonymous. Typically, products with a size of about 200×60×50 mm orsmaller and an overall weight of about 250 g or lighter, preferablyabout 150 g or even about 100 g or lighter, are considered portable. Theterm ‘portable’ further means that, during use and/or “on the go”, thedevice is fully operable without an attached cable power source and/orwithout the need to be connected to a stationary workstation (such as adedicated docking station, personal computer, or the like); forinstance, the portable spirometer of the invention does not need to beplugged into a power socket for the user to be able to perform fullspirometry measurements. So-called table-top devices, in particulartable-top spirometers, as commonly employed in clinical settings, arenot considered ‘portable’ in the sense of the present invention. Whiletheoretically some of these table-top devices could still be lifted andcarried around by a human user without additional help, too, it wouldtypically not be considered comfortable for longer times (e.g. a wholeday), and/or would require the use of a dedicated casing (e.g. asuitcase) and/or the use of both hands.

Any reference signs in the claims should not be construed as alimitation to the embodiments represented in any of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

In a first aspect, the invention provides a portable electronicspirometer (1) comprising (a) a tubular mouthpiece (2) with a proximalopening (3) for insertion into the mouth of a user, a distal opening(4), a main fluid channel (5) extending between the proximal opening (3)and the distal opening (4), a first lateral opening (6), a secondlateral opening (7) positioned at a longitudinal distance to the first,and a flow restrictor (8) positioned in the main fluid channel (5)between the first and the second lateral opening (6 and 7); and

(b) a main body (9) with a first fluid opening (10) connectible with thefirst lateral opening (6) of the mouthpiece (2), a second fluid opening(11) connectible with the second lateral opening (7) of the mouthpiece(2), a bypass fluid channel (12) extending between the first and thesecond fluid opening (10 and 11), a MEMS-based thermal fluid flow sensor(13) which is positioned at the bypass fluid channel (12) for generatinga signal in response to the fluid flow in the bypass fluid channel (12),and a microcontroller (14) connected with the fluid flow sensor (13) forcalculating the fluid flow from the signal generated by the flow sensor(13). One embodiment of this spirometer (1) is depicted in FIG. 2 forinstance.

Optionally, the tubular mouthpiece (2) and the main body (9) may bedetachable from one another. Further optionally, the connection betweenthe first fluid opening (10) of the main body (9) with the first lateralopening (6) of the mouthpiece (2) and/or between the second fluidopening (11) of the main body (9) with the second lateral opening (7) ofthe mouthpiece (2) may be achieved by a snap-fit mechanism. Preferably,the mouthpiece (2) is designed to fit the main body (9) in only one way,or direction; preventing misplacement and/or incorrect assembly of thetwo parts.

One advantage of the spirometer (1) is that at a size of about 115×55×45mm and a weight below 100 g, the device is both light weight and small,pocket-sized, handheld and thus easily portable by a user (e.g. in acoat pocket, trousers pocket or a handbag), while at the same timeallowing for full spirometry as defined by the spirometry standards ofthe American Thoracic Society (ATS), the European Respiratory Society(see e.g. Eur Respir J 1997; 10: Suppl. 24, 2s-8s; or “Standardisationof spirometry”; Eur Respir J 2005; 26: 319-338) or ISO 26782:2009(specifying the requirements for spirometers intended for the assessmentof pulmonary function in humans weighing more than 10 kg) at very highprecision; including measurements during both inhalation and exhalationand providing all functions of spirometers as used in hospital settings.The device is further capable to fulfil the peak expiratory flowstatement by the ERS (see e.g. “Peak expiratory flow: conclusions andrecommendations of a Working Party of the European RespiratorySociety”).

The basic functionality of the spirometer (1) includes the measurementof exhalatory and inspiratory fluid flow rates, time and volume ofexhalation and inspiration, as well as calculation of all spirometricparameters of interest, including the most common: FVC, FEV₁, PEF andFEV₁% but also parameters such as FEV₆, FRC, SVC, MW or ERV, in order toassess the respiratory function of a user (e.g. a patient suffering froma respiratory disease, or an athlete).

Additionally, the spirometer (1) will continuously monitor the localenvironmental parameters, such as temperature, pressure and ambient airhumidity, as will be detailed further below. This may, for instance, beachieved by monitor the local environmental parameters at a predefinedmonitoring frequency, or monitoring interval (e.g. 10 seconds for everyone hour, every half hour or every quarter hour, or the like). Likethis, the user of the spirometer (1) not only measures and receives thespirometric data with regards to his/her lung function, but can alsomatch specific data points to e.g. the environmental parameters at, oraround, the spirometric measurement time point.

A further advantage is that the spirometer (1) may be used by laypeople, i.e. without medical or similarly trained staff as currentlyrequired for most spirometry tests in doctor's offices and/or hospitalsettings; thus providing users with an ‘in-home’ spirometer which theycan use by themselves. In that regard, it should be understood that inthe context of this invention, users are not necessarily patientsafflicted with respiratory diseases. The parameters used to examine therespiratory tract are also helpful e.g. for athletes training regularly,enabling them to monitor their training progress and track theirperformance; or for smokers wanting to evaluate the benefits of theirsmoking cessation.

Advantageously, the spirometer (1) may be connected to a user's personalcomputer and/or smartphone, preferably via a dedicated proprietaryspirometer application (‘app’) with proprietary and predictivealgorithms; or as an ‘add-on’ integrated in existing healthcare appsavailable for iOS or Android smartphones.

Furthermore, the spirometer (1) of the invention is fully electronic anddoes not comprise any moving parts, such as rotating turbines oroscillating cantilevers as they are common for measuring the fluid flowin prior art spirometers, thus obviating the need for regular, frequentexternal calibrations. Further, it turns on quickly with less than 7seconds between switching the spirometer (1) on and the device beingready for use. This is not only energy-efficient and thus saving batterylife, but also renders the device suited to be used “on the go” bymedical staff such as doctors; for instance, during ward rounds, homevisits, etc.

MEMS-based thermal fluid flow sensors (13) provide a high sensitivityfor fluid flow measurements, yet at the same time suffer from aninherent detrimental susceptibility to vibration; i.e. any flowmeasurement attempts are per se affected by non-flow-related vibrationsas they occur e.g. when the user moves the spirometer during use. Thismay be one of the reasons, why—according to the current knowledge of theinventors—no operable, fully functional spirometer comprising aMEMS-based thermal fluid flow sensor has actually been developed before.The invention is based on the unexpected discovery that a MEMS-basedthermal fluid flow sensor (13) can be incorporated in a portableelectronic spirometer in such a way that accurate and reproducible, orprecise, (full) spirometric flow measurements are enabled, and unlikemany other devices further allows both inspiratory and expiratory lungfunction assessments. This is achieved by positioning the MEMS-basedthermal fluid flow sensor (13) at a bypass fluid channel (12) andproviding a flow restrictor (8) in order to redirect specific fractionsof the air flow in the main fluid channel (5) to the bypass fluidchannel (12). When incorporated in the spirometer (1) in this way, theMEMS-based thermal fluid flow sensor (13) provides a higher precision,reproducibility and sensitivity than the different flow sensorstypically used in prior art portable spirometers, such as fan-basedtransducers (turbines). Additionally, by placing the MEMS-based thermalfluid flow sensor (13) in the bypass fluid channel (12) comprised in themain body (9) of the spirometer (1), it is protected from directexposure to saliva and/or bioparticles that could damage it, or affectthe accuracy and/or precision of measurements.

The precision, reproducibility and sensitivity may be increased furtherby using an acceleration sensor (15) which is not connected to the mainfluid channel (5) or the bypass fluid channel (12) in addition to theMEMS-based thermal fluid flow sensor (13). This acceleration sensor(15), preferably an acceleration sensor (15) which is incorporatedwithin the portable electronic spirometer (1), in particular within themain body (9) the portable electronic spirometer (1), allows for thecorrection of the calculated fluid flow as will be detailed furtherbelow. The acceleration sensor (15) further allows for alerting the userif movement is detected during measurements and, if needed, to instructthe user to correct his/her position, and/or to disregard incorrectlyperformed manoeuvres in long term analysis (e.g. manoeuvres withsubstantial head movement); thereby improving the quality of the singlemanoeuvre as well as the long term analysis of lung function parameters.In final consequence, the acceleration sensor (15) also allows for aclinically relevant improvement of the sensitivity, accuracy, andreproducibility, or precision, of the spirometric flow measurements ofthe spirometer (1).

In one embodiment, the mean accuracy of the spirometer (1) fulfillsATS/ERS criteria; i.e. the parameters determined with the spirometer (1)of the invention differ not more than the allowed values from thereference flow curves (see accuracy tests for spirometers in“Standardisation of spirometry”; Eur Respir J 2005; 26: 319-338, on page333; or ISO 26782:2009 which specifies requirements for spirometersintended for the assessment of pulmonary function in humans weighing >10kg). Even at low flow rates below 0.3 L/sec, the accuracy is maximally±3%. The repeatability, or in other words the reproducibility orprecision, is ±0.5%.

In fact, the use of a MEMS-based thermal fluid flow sensor (13) in thespirometer (1) of the invention as claimed, and preferably a spirometer(1) with an incorporated acceleration sensor (15) which is not connectedto the main fluid channel (5) or the bypass fluid channel (12) inaddition to said MEMS-based thermal fluid flow sensor (13), renders thedevice sensitive enough to even measure the minute movements of airmoved in or out of the trachea by the heart beat, enabling new medicaluses which were not available before with prior art spirometers.

A yet further advantage of the inventive spirometer (1), in particular,for embodiments where the mouthpiece (2) and the main body (9) aredetachable from one another, is that because the MEMS-based thermalfluid flow sensor (13) is positioned at the bypass fluid channel (12)comprised in the main body (9), the mouthpiece (2) may be detachedeasily and safely from the main body (9) without the risk of potentiallydamaging said flow sensor (13), or otherwise affecting the accuracyand/or precision of its measurements. This overcomes the limitations ofprior art devices in which only the accurate (re)placement of adetachable mouthpiece into a main body ensured proper functioning aswell as accuracy and precision of the flow sensor, e.g. a pressuresensor. The spirometer (1) of the invention comprises a mouthpiece (2)designed to fit the main body (9) in only one way, or direction;preventing misplacement and/or incorrect assembly of the two parts, asdescribed above.

The main fluid channel (5) of the tubular mouthpiece (2) is typicallyshaped as a hollow circular cylinder or as an elliptical cylinder,partially in order to resemble the shape of the opened mouth of a userupon inhaling or exhaling through the main fluid channel. Optionally,the cylinder may be slightly tapered towards the distal opening (4); forinstance, gradually narrowing from an outer diameter of about 31 mm atthe proximal opening (3) to an outer diameter of about 29 mm at thedistal opening (4) over a length of about 110 to 120 mm.

In general, the diameter of the main fluid channel (5) at the proximalopening (3) should be chosen such as to comfortably fit the mouth of theintended user and allow him/her to effectively seal the mouthpiece (2)with the lips. For instance, a diameter at the proximal opening (3) ofabout 30 mm for adult users would be suitable and smaller diameters forinfants or kids. Optionally, a small groove, or ridge, may be providedfor the user's teeth in order to improve the seal between lips andmouthpiece (2).

In the embodiment as depicted in FIG. 1A-C, the front end (2.1) of thetubular mouthpiece (2), i.e. the end comprising the proximal opening (3)is configured as an integral part of the tubular mouthpiece (2).Alternatively, this front end (2.1) may be configured as a detachablepart of the tubular mouthpiece (2), allowing to remove this front end(2.1) portion of the mouthpiece (2) in order to either clean it, ordiscard and replace it, after contact with a user's lips and/or tongue.A detachable front end (2.1) facilitates cleaning and enables the use ofdisposable parts in multi-patient settings (where applicable).

As mentioned, the flow restrictor (8) is an integral part of thespirometer (1) which—in combination with the bypass fluid channel(12)—enables accurate and reproducible, or precise, measurements of theair flow in the main fluid channel (5) by the MEMS-based thermal fluidflow sensor (13; or hereafter also shortly referred to as the flowsensor (13)).

The flow restrictor (8) is employed in order to direct some of the fluidflow, namely the inhaled or exhaled air stream, which passes through themain fluid channel (5) into the bypass fluid channel (12) and past theflow sensor (13). This is important because the flow sensor (13) ishighly sensitive; i.e. by redirecting only a fraction of the fluid flowin the main fluid channel (5) through the bypass fluid channel (12), theflow sensor (13) is enabled to generate signals which have a highcorrelation with the fluid flow in the main fluid channel (5).Furthermore, the flow sensor (13) is sensitive to vibrations, or noises,which may result from a movement or acceleration of the device;therefore, shielding it from the main fluid channel (5) further helps toensure precise and accurate fluid flow measurements.

In one embodiment, the flow restrictor (8) in the spirometer (1)exhibits a flow resistance, or impedance, in the range from about 0.01to about 0.2 kPa/(L/s), preferably from about 0.01 to about 0.15kPa/(L/s), and more preferably from about 0.01 to about 0.1 kPa/(L/s) ata fluid flow of 60 SLM to 900 SLM (or SLPM; standard liter per minute);and/or the flow restrictor (8) is adapted or configured such as to causea fluid flow in the bypass fluid channel (12) which is from about 1:10to about 1:200 of the fluid flow in the main fluid channel (5). In otherword, the fluid flow in the bypass channel (12) may range from about 0.3SLM to about 90 SLM. The flow resistance thus falls below the maximumvalue of 0.15 kPa/(L/s) at a fluid flow of 840 SLM as required by the“Standardisation of spirometry” (as published e.g. by the AmericanThoracic Society (ATS) or the European Respiratory Society (ERS) in EurRespir J 2005; 26: 319-338).

In one embodiment, the flow restrictor (8) is a perforated disk (8.1)having a cross-sectional orientation with respect to the main fluidchannel (5), i.e. a fixed, or immobile or immovable, mechanical flowrestrictor (8) which is being arranged perpendicular to the main fluidchannel's (5) longitudinal axis and having a diameter matching the innerdiameter of the channel (5), such as to allow fluid flow only throughthe perforations (8.2) of the disk (8.1). In other words, the portableelectronic spirometer (1) of this embodiment comprises:

(a) a tubular mouthpiece (2) with a proximal opening (3) for insertioninto the mouth of a user, a distal opening (4), a main fluid channel (5)extending between the proximal opening (3) and the distal opening (4), afirst lateral opening (6), a second lateral opening (7) positioned at alongitudinal distance to the first lateral opening (6), and a flowrestrictor (8) positioned in the main fluid channel (5) between thefirst and the second lateral opening (6 and 7), wherein said flowrestrictor (8) is a perforated disk (8.1) having a cross-sectionalorientation with respect to the main fluid channel (5); and(b) a main body (9) with a first fluid opening (10) connectible with thefirst lateral opening (6) of the mouthpiece (2), a second fluid opening(11) connectible with the second lateral opening (7) of the mouthpiece(2), a bypass fluid channel (12) extending between the first and thesecond fluid opening (10 and 11), a MEMS-based thermal fluid flow sensor(13, 13.1, 13.2) positioned at the bypass fluid channel (12) forgenerating a signal in response to the fluid flow in the bypass fluidchannel (12), anda microcontroller (14) connected with the fluid flow sensor (13, 13.1,13.2) for calculating the fluid flow from the signal generated by theflow sensor (13, 13.1, 13.2). A perforated disk (8) is advantageous, forinstance, in comparison to a venturi section in the flow channel, inthat it can be exchanged more easily to e.g. adjust flow restrictionvalues (such as for adults, kids, infants). Optionally, the mouthpiece(2) may comprise a dedicated groove into which the perforated disk (8)can be slid such as to be fixed, or immobilized, within the mouthpiece(2) during transport and/or use of the spirometer (1). The perforateddisk (8) further allows to sustain a laminar air flow which is vital toavoid unpredicted turbulences in the main fluid channel (5) and thebypass fluid channel (12).

In one embodiment, the perforated disk (8.1) exhibits from about 1 toabout 100 perforations, or from about 2 to about 100 perforations, orfrom about 4 to about 100 perforations (8.2), or from about 15 to about100 perforations (8.2). For instance, the perforated disk (8.1) mayexhibit from about 1 to about 24 perforations, or from about 2 to about21 perforations, or from about 4 to about 18 perforations, or from about6 to about 12 perforations; or from about 30 to about 85 perforations,or from about 45 to about 70 perforations. These perforations (8.2) maybe shaped as sectors of a circle or oval; or they may be circular,elliptic or polygonal in shape; or they may exhibit an irregular shape.Optionally, perforations of more than one shape may be combined witheach other Alternatively or in addition, these perforations (8.2) mayexhibit a total combined area of all perforations (8.2) ranging fromabout 26% to about 96%, or from about 39% to about 96%, or from about26% to about 72%, of the cross-sectional area of the main fluid channel(5) at the position of the perforated disk (8.1). In other words fromabout 26% to about 96%, or from about 39% to about 96%, or from about26% to about 72%, of the cross-sectional area of the perforated disk(8.1) is open/perforated (this area also being referred to herein as the‘perforated area’); such as from about 30% to about 96%, or from about39% to about 96% (e.g. about 39%, or about 76%, or about 96%), or fromabout 30% to about 60%, or from about 30% to about 50% (e.g. about 30%),or from about 40% to about 50% (e.g. about 43% or about 45%).

The smaller ‘perforated areas’ values from about 30% to about 60% aremore common, though not exclusively, for perforated disks (8.1)exhibiting a multitude of circular or hexagonal perforations (e.g. inthe range from about 15 to about 100 perforations). The larger‘perforated areas’ values from about 60% to about 96% are more common,though not exclusively, for perforated disks (8.1) exhibiting fewer butlarger perforations.

For all embodiments, the ‘perforated area’ is controllable via theadjustment of the number of perforations and/or the adjustment of thesize, or surface area, of the perforations. For the embodiments, wherethe perforation(s) is/are shaped by a rib (8.3), or a plurality of ribs(8.3), the ‘perforated area’ is controllable via the adjustment of thenumber of ribs and/or the adjustment of their size, or surface area, ofthe ribs.

In a specific embodiment, the flow restrictor (8) is a perforated disk(8.1) with about 35 to about 80, or about 45 to about 70, perforations(8.2) exhibiting a ‘perforated surface area’ of from about 26% to about96% of the perforated disk's (8.1) total surface area. In a furtherspecific embodiment, the flow restrictor (8) is a perforated disk (8.1)with a total surface area of about 587 mm² and 55 perforations (8.2)exhibiting a ‘perforated surface area’ of about 175 mm², or about 30% ofthe perforated disk's (8.1) total surface area. In a yet furtherspecific embodiment, the perforations (8.2) are shaped as regularhexagons, as depicted exemplarily in FIG. 3A.

In another specific embodiment, the flow restrictor (8) is a perforateddisk (8.1) with a total surface area of about 587 mm² and 37perforations (8.2) exhibiting a ‘perforated surface area’ of about 262mm², or about 45% of the perforated disk's (8.1) total surface area. Ina more specific embodiment, the perforations (8.2) exhibit a circularshape, as depicted exemplarily in FIG. 3B.

In a further specific embodiment, the flow restrictor (8) is aperforated disk (8.1) where the perforations are shaped as sectors of acircle or oval, said sectors being formed by a rib, or ribs (8.3), whichdissect(s) a circular or oval opening, across its complete diameter,forming perforations (8.2) shaped as sectors of a circle, or oval. Thiscircular or oval opening may be formed by an internal crosssection ofthe main fluid channel (5). Alternatively, the perforated disk (8.1) maycomprise an outer ring (8.4) whose larger outer diameter matches theinner diameter of the main fluid channel (5) of the spirometer (1) andwhose smaller inner diameter defines a central opening (e.g. a circularor oval opening). In this embodiment, the rib, or ribs (8.3), may extendfrom the outer ring (8.4), with each rib (8.3) contacting the ring (8.4)at two points, such that the circular, or oval, central opening isdissected across its complete diameter by the ribs (8.3), andperforations (8.2) shaped as sectors of a circle, or oval, are formed(as depicted exemplarily in FIG. 3C). Further alternatively, the rib, orribs (8.3) may extend from said outer ring (8.4) towards the center ofsaid central opening, but with each rib (8.3) contacting the outer ring(8.4) at only one point, thereby dissecting the central opening onlypartially rather than completely, and forming irregularly shapedperforations (8.2), as depicted exemplarily in FIG. 3D.

Where the perforations are shaped as sectors of a circle, or oval, theribs (8.3) dissecting said circle, or oval, across its complete diametermay have a breadth of from about 0.1 mm to about 4 mm, or from about 1mm to about 3 mm, or from about 1.5 mm to about 2.5 mm, such as 1.9 mm,1.95 mm or 2 mm. These ribs (8.3) may be straight as depicted e.g. inFIG. 3C.

For embodiments where the rib, or ribs (8.3), do not extend across thecomplete diameter (e.g. as depicted in FIG. 3D) the rib, or ribs, may beeven broader; for instance, from about 0.1 mm to about 15 mm, or fromabout 1 mm to about 12 mm, or from about 1.5 mm to about 10 mm, or fromabout 1.7 mm to about 8 mm, or from about 2 mm to about 6 mm. This rib,or these ribs (8.3), may be straight as depicted in FIG. 3D. Further,this rib, or these ribs (8.3), may exhibit a rectangular shape, also asdepicted in FIG. 3D.

In a specific embodiment, the flow restrictor (8) is a perforated disk(8.1) with a total surface area of about 587 mm² and 1-6 perforation(s)(8.2), dissected by ribs (8.3) and exhibiting a ‘perforated surfacearea’ of about 232-562 mm², or about 39-96% of the perforated disk's(8.1) total surface area. In a further specific embodiment, the flowrestrictor (8) is a perforated disk (8.1) with a total surface area ofabout 587 mm² and 1-6 perforation(s) (8.2), dissected by ribs (8.3), thedisk (8.1) exhibiting a ‘perforated surface area’ of about 447 mm², orabout 76% of the perforated disk's (8.1) total surface area. In a morespecific embodiment, the flow restrictor (8) is a perforated disk (8.1)with a total surface area of about 587 mm² and 2-6 perforations (8.2)which are shaped as sectors of a circle or oval; for instance, 6perforations (8.2) dissected by 3 ribs (8.3) which extend from an outerring (8.4) as depicted exemplarily in FIG. 3C.

The embodiments using a rib, or ribs (8.3) to define the size and shapeof the perforations (8.2) may be preferred in that they allow verysmooth airflow with little turbulence, and a signal with limited noisein the main fluid channel (5). In addition, they are typically easy toprepare using, for instance, molding or 3D-printing techniques.

With regard to the ‘perforated area’ of the perforated disk (8.1), itshould be understood that this area also depends on the dimensions ofthe bypass fluid channel (12), or is adjusted in relation thereto. Ife.g. the crossectional area of the bypass fluid channel (12) is larger,more air may be redirected there; so, the perforated disk (8.1) shouldexhibit a larger ‘perforated area’ as well. In one embodiment, the ratioof the ‘perforated area’ of the perforated disk (8.1) to thecrossectional area of the bypass fluid channel (12) ranges from about150 to about 350, such as 250. However, it should be understood, thatthe exact ratio of the ‘perforated area’ of the perforated disk (8.1) tothe crossectional area of the bypass fluid channel (12) is of lowerrelevance as long as the flow restrictor (8) causes a fluid flow in thebypass fluid channel (12) which is from about 1:10 to about 1:200 of thefluid flow in the main fluid channel (5) and/or ranging from about 0.3SLM to about 90 SLM.

The perforated disks (8.1) may be prepared by any technique suited toprovide perforations of the desired shape and size which is needed forproviding a flow resistance, or impedance, in the range from about 0.01to about 0.2 kPa/(L/s); and/or to cause a fluid flow in the bypass fluidchannel (12) which is from about 1:10 to about 1:200 of the fluid flowin the main fluid channel (5). This can be achieved for instance bycutting or die-cutting the perforations (8.2) into the disk (8.1) usinge.g. a laser cutter or water jet cutter, a die cutter, a punch, or thelike. Alternatively, the disk (8.1) may be molded or otherwise‘positively’ formed, such as by 3D-printing techniques. In other words,the term ‘perforation’ is used herein synonymously to ‘opening’, or‘hole’ or the like, and is not intended to imply a specific preparationmethod which necessarily involves cutting, punching or stamping orsimilar techniques which form the perforations by removing material fromthe blank disk.

In order to advantageously allow molding the perforated disk (8.1) asone single piece, it was modified in comparison to those used in e.g.industrial gas flow measurement applications. In one embodiment, theflow restrictor (8) is a perforated disk (8.1) with a width, orthickness, of about 2 to 4 mm. In a further embodiment, the perforateddisk (8.1) is molded or 3D-printed and exhibits a width, or thickness,of about 1 to 4 mm. In a yet further embodiment, the perforated disk(8.1) exhibits a width, or thickness, of about 1 to 4 mm, a totalsurface area of about 587 mm² and 2 to 6 perforations (8.2) shaped assectors of a circle or oval, dissected by straight ribs (8.3) with awidth of about 1.5 mm to about 2.5 mm (e.g. 1.9 mm or 2 mm); and a‘perforated surface area’ of about 39 to 96% (e.g. 76%) of theperforated disk's (8.1) total surface area. Perforated disks (8.1) withstraight ribs dissecting a circle, or oval, into sectors (e.g. into 6sectors) may be preferred in that they are typically easy to mold orprint.

In one embodiment, the distance between the flow restrictor (8) and thefirst lateral opening (6) along the longitudinal axis of the main fluidchannel (5) of the spirometer (1) is from about 5 mm to about 15 mm, andpreferably from about 8 mm to about 12 mm, e.g. 10.0 mm; and thedistance between the flow restrictor (8) and the second lateral opening(7) from about 25 mm to about 45 mm, and preferably from about 30 mm toabout 40 mm, e.g. 34.2 mm. However, it should be understood, that theexact spacing of the flow restrictor (8) between the first and secondlateral opening (6 and 7) is of lower relevance as long as the flowrestrictor (8) causes a fluid flow in the bypass fluid channel (12)which is from about 1:10 to about 1:200 of the fluid flow in the mainfluid channel (5) and/or ranging from about 0.3 SLM to about 90 SLM.

In one embodiment, the MEMS-based thermal fluid flow sensor (13) of thespirometer (1) is a bidirectional flow sensor (13.1), such as to allowe.g. for measurements during both inhalation and exhalation. In thisconfiguration, the MEMS-based thermal fluid flow sensor (13, 13.1)enables the determination of all relevant spirometry parameters: FVC,FEV1, FEV_(1%), PEF, FEF_(25-75%), FET, EVOL, ELA, VC, IVC, IC, ERV,FEV₁/FVC_(%), FEV_(0.5), FEV_(0.5)/FVC_(%), FEV_(0.75),FEV_(0.75)/FVC_(%), FEV₂, FEV₂/FVC %, FEV₃, FEV₃/FVC_(%), FEV₆,FEV₁/FEV_(6%), FEF_(25%), FEF_(0.50%), FEF_(0.75%), FEF₇₅₋₈₅, FIVC,FIV₁, FIV₁/FIVC_(%), FIF_(0.25%), FIF_(50%). The most commonly evaluatedparameters are FVC, FEV, FEV₁, PEF.

In a more specific embodiment, the MEMS-based thermal fluid flow sensor(13) is a monolithic CMOS flow sensor (13.2; complementarymetal-oxide-semiconductor) comprising a sensor chip, the chip comprisingan encapsulated gas bubble, a microheater for heating the gas bubble, afirst plurality of thermopiles located on a first side of the gasbubble, and a second plurality of thermopiles located on a second sideof the gas bubble which is opposite to the first side. In a preferredembodiment, the thermopiles are symmetrically positioned upstream anddownstream of the micro-heater, such that in the presence of fluid flow,or gas flow, the thermopiles will show temperature differences fromwhich a) the fluid flow may be calculated, and b) the exhale temperaturecan be determined; i.e. such a monolithic CMOS flow sensor (13.2) alsoacts as a breath temperature sensor (26). The sensor chip can be mountedon a printed circuit board along with e.g. the microcontroller (14) asdepicted in FIG. 4 .

In a specific embodiment, the communication of the MEMS-based thermalfluid flow sensor (13, 13.1, 13.2) with the microcontroller (14) isachieved via a so-called SPI bus (serial peripheral interface).

The MEMS-based thermal fluid flow sensor (13, 13.1, 13.2)—or hereaftershortly referred to as the flow sensor (13, 13.1, 13.2)—is positioned atthe bypass fluid channel (12) for generating a signal in response to thefluid flow in the bypass fluid channel (12). As mentioned, the bypassfluid channel (12) extends from the first to the second fluid opening(10 and 11), and therefore—as long as the tubular mouthpiece (2) and themain body (9) of the spirometer (1) are attached to each other—also fromthe first to the second lateral opening (6 and 7) of the tubularmouthpiece (2), such that a fluid communication between the main fluidchannel (5) and the bypass fluid channel (12) is provided. In oneembodiment, the bypass fluid channel (12) has a parallel orientation toand extends over a longitudinal portion of the main fluid channel (5).This may be seen e.g. in FIG. 2 .

In one embodiment, the spirometer (1) further comprises an accelerationsensor (15) which is different from the flow sensor (13, 13.1, 13.2), asshown for instance in FIG. 4 . In other words, the portable electronicspirometer (1) of this embodiment comprises:

(a) a tubular mouthpiece (2) with a proximal opening (3) for insertioninto the mouth of a user, a distal opening (4), a main fluid channel (5)extending between the proximal opening (3) and the distal opening (4), afirst lateral opening (6), a second lateral opening (7) positioned at alongitudinal distance to the first lateral opening (6), and a flowrestrictor (8) positioned in the main fluid channel (5) between thefirst and the second lateral opening (6 and 7); and(b) a main body (9) with a first fluid opening (10) connectible with thefirst lateral opening (6) of the mouthpiece (2), a second fluid opening(11) connectible with the second lateral opening (7) of the mouthpiece(2), a bypass fluid channel (12) extending between the first and thesecond fluid opening (10 and 11), a MEMS-based thermal fluid flow sensor(13, 13.1, 13.2) positioned at the bypass fluid channel (12) forgenerating a signal in response to the fluid flow in the bypass fluidchannel (12), an acceleration sensor (15, 15.1) which is different fromthe MEMS-based thermal fluid flow sensor (13, 13.1, 13.2), and amicrocontroller (14) connected with the fluid flow sensor (13, 13.1,13.2) for calculating the fluid flow from the signal generated by theflow sensor (13, 13.1, 13.2).

It should be understood, that this acceleration sensor (15) ispreferably incorporated within and/or an integral part of the spirometer(1), usually as part of the spirometer's main body (9), e.g. on theprinted circuit board; in other words, the acceleration sensor (15) isnot provided separate or external from the spirometer (1). This set-upis selected to ensure that, while being different from the flow sensor(13, 13.1, 13.2), the acceleration sensor (15) is still exposed to thesame or very similar external influences (such as temperature, movement,vibration, etc.) as the flow sensor (13, 13.1, 13.2); and/or, to ensurethat the sensitivity achieved is matching the sensitivity needed forhigh precision spirometry. Same as the flow sensor (13, 13.1, 13.2),this acceleration sensor (15) is directly or indirectly connected withthe microcontroller (14) such that the microcontroller (14) is capableof receiving a signal from the acceleration sensor (15). Theacceleration sensor (15) can, for instance, be mounted on a printedcircuit board along with e.g. the flow sensor (13, 13.1, 13.2) and themicrocontroller (14) as depicted in FIG. 4 . However, unlike the flowsensor (13, 13.1, 13.2), this acceleration sensor (15) is not connectedto the main fluid channel (5) or the bypass fluid channel (12), such asto generate signals which are predominantly related to vibrations, ornoises, caused by movements, or accelerations, of the spirometer (1).

In one of the preferred embodiments, the portable electronic spirometer(1) comprises:

(a) a tubular mouthpiece (2) with a proximal opening (3) for insertioninto the mouth of a user, a distal opening (4), a main fluid channel (5)extending between the proximal opening (3) and the distal opening (4), afirst lateral opening (6), a second lateral opening (7) positioned at alongitudinal distance to the first lateral opening (6), and a flowrestrictor (8) positioned in the main fluid channel (5) between thefirst and the second lateral opening (6 and 7), wherein said flowrestrictor (8) is a perforated disk (8.1) having a cross-sectionalorientation with respect to the main fluid channel (5); and(b) a main body (9) with a first fluid opening (10) connectible with thefirst lateral opening (6) of the mouthpiece (2), a second fluid opening(11) connectible with the second lateral opening (7) of the mouthpiece(2), a bypass fluid channel (12) extending between the first and thesecond fluid opening (10 and 11), a MEMS-based thermal fluid flow sensor(13, 13.1, 13.2) positioned at the bypass fluid channel (12) forgenerating a signal in response to the fluid flow in the bypass fluidchannel (12), an acceleration sensor (15, 15.1) which is different fromthe MEMS-based thermal fluid flow sensor (13, 13.1, 13.2); and amicrocontroller (14) connected with the fluid flow sensor (13, 13.1,13.2) for calculating the fluid flow from the signal generated by theflow sensor (13, 13.1, 13.2).

The flow restricting perforated disk (8.1) in the above describedpreferred embodiment may be any one of the perforated disks (8.1)described earlier, preferably a perforated disk (8.1) comprising fromabout 2 to about 100 perforations, or from about 4 to about 100perforations (8.2), or from about 15 to about 100 perforations (8.2);for instance, a perforated disk (8.1) with a total surface area of about587 mm² and 55 hexagonal perforations (8.2) with a ‘perforated surfacearea’ of about 175 mm², or 37 circular perforations (8.2) with a‘perforated surface area’ of about 262 mm², or 6 perforations (8.2)shaped as sectors of a circle, or oval with a ‘perforated surface area’of about 447 mm².

As mentioned, the flow sensor (13, 13.1, 13.2) is rather sensitive tovibrations, or noises, resulting e.g. from a movement or acceleration ofthe spirometer (1). Therefore, an additional acceleration sensor (15)which is not connected to the main fluid channel (5) or the bypass fluidchannel (12), but incorporated within the spirometer (1), in particularwithin the main body (9) of the spirometer (1), allows for thecorrection of the calculated fluid flow in that they detect suchnon-flow-related vibrations, or noises, and enable the subtraction of itfrom the fluid flow signal generated by the flow sensor (13, 13.1,13.2), and/or allow for the verification that a measurement of the flowsensor (13, 13.1, 13.2) was performed under suitable conditions (such aswithout significant noise).

In one embodiment, the microcontroller (14) of the spirometer (1) isprogrammed to calculate a corrected fluid flow from the signal generatedby the flow sensor (13, 13.1, 13.2) and from a signal generated by theacceleration sensor (15). In a specific embodiment, the microcontroller(14) is connected both with the fluid flow sensor (13, 13.1, 13.2) andthe acceleration sensor (15, 15.1) and is programmed to calculate acorrected fluid flow from the signal generated by the flow sensor (13,13.1, 13.2) and from a signal generated by the acceleration sensor (15,15.1).

In a more specific embodiment, the acceleration sensor (15) is a 3-axissensor (15.1) with a sensitivity (So) of at least 973 counts/g±5% foreach of the three axes; typically, the sensitivity ranges between 973and 1075 counts/g; e.g. 1024 counts/g; for instance, a MMA8491QR1 unitas supplied by Freescale Semiconductors. This MMA8491QR1 unit is a lowvoltage, multifunctional digital 3-axis, 14-bit±8 g accelerometer housedin a 3×3 mm casing and may communicate with the microcontroller (14) viaa common inter-integrated circuit bus (I²C bus), or I²C interface. Itcovers an acceleration range of ±8 per axis and data may be read fromthe sensor with 1 mg/LSB sensitivity.

It was surprisingly found that the use of a MEMS-based thermal fluidflow sensor (13, 13.1, 13.2) in the spirometer (1) of the invention asclaimed, together with an incorporated acceleration sensor (15, 15.1)and a perforated disk (8.1) flow restrictor, provides a remarkably highprecision to the inventive spirometer (1) In fact, it renders the devicesensitive enough to even measure the minute movements of air moved in orout of the trachea by the heart beat, thus enabling not only fullspirometry as intended but also new medical uses which were notavailable before with prior art spirometers; for instance, highprecision full spirometry in connection with the possibility to monitorthe heart beat frequency of a patient simultaneously. According to theknowledge of the inventors, such high precisions could not be achievedin the past with prior art portable devices which are evaluating thefluid flow by measuring either a pressure difference before and after aflow restrictor with a known resistance (e.g. using a differentialpressure sensor), or by the rotations of a turbine.

In addition, the device may be manufactured easily and at lowmanufacturing costs, allowing to offer a low-priced, lightweight,energy-efficient, yet highly precise portable electronic spirometer (1),which does not require large and/or heavy energy sources.

In one embodiment, the acceleration sensor (15, 15.1) is furtheremployed for measuring the temperature of the breath; similar to theMEMS-based thermal fluid flow sensor (13, 13.1, 13.2).

In one embodiment, the electronic spirometer (1) further comprises agyroscope in addition to the acceleration sensor (15, 15.1). Thegyroscope detects the horizontal orientation of the spirometer (1) andcan be used to detect non-perpendicular orientation of the device duringa spirometric measurement manoeuvre. This allows for automaticallyalerting the user to correct his/her position, and thus for furtherimproved quality of the single manoeuvre as well as the long termanalysis of lung function parameters; in particular, of unsupervisedand/or laypersons' spirometry manoeuvres.

In one embodiment, the spirometer (1) further comprises a heart ratesensor (16), a blood oxygen saturation sensor (17; also called pulseoximetry sensor or SpO2 sensor), a temperature sensor for measuring thetemperature of the environment (18), an atmospheric pressure sensor(19), and/or a moisture sensor (20; also called humidity sensor). Eachof these one or more sensors (16-20) is directly or indirectly connectedwith the microcontroller (14) such that the microcontroller (14) iscapable of receiving a signal from each of the one or more sensors(16-20).

In one embodiment, the heart rate sensor (16) and the blood oxygensaturation (17) are contained within one and the same sensing means,i.e. a combined sensor as depicted e.g. in FIG. 2 . In a specificembodiment, this combined sensor operates by reflecting light waves oftwo distinct wavelengths—usually red (about 600-750 nm) and infrared(about 780 nm-1 mm)—from a vascularized tissue and measuring theremitted light (i.e. reflected or scattered) with a recipientphotodiode. Typically, these combined sensors allow two operation modes:SpO2 (red and infrared diodes switched on interchangeably) or heart rateonly (only infrared diode switched on). In a more specific embodiment,the combined heart rate and blood oxygen saturation (16, 17) is aMAX30100 module as supplied by Maxim Integrated. The system comprises ared diode, an infrared diode and a photodiode, as well as filteringblocks and digital signal processing units including a I²C (TWI) digitalinterface. Communication with the sensor allows to control the samplingparameters and current of both light diodes, providing the possibilityof dynamically correcting the amplitude of the output signal. Samplingfrequencies range within 50 Hz to 1 kHz, corresponding to illuminatingtimes of the diodes from 200 μs to 1600 μs.

Optionally, the blood oxygen saturation (17)—or the combined heart rateand blood oxygen saturation (16, 17)—is housed in the spirometer's (1)main body (9) in such a way that the user's fingers naturally cover theblood oxygen saturation (17) while holding the spirometer (1) in handduring the inhalation and/or exhalation manoeuvres, as is depicted inFIG. 2 .

In one embodiment, the spirometer (1) comprises all three environmentalsensors, namely the temperature sensor, the atmospheric pressure sensorand the moisture sensor (18-20). In a more specific embodiment, one orall of these environmental sensors (18-20) are supplied with 3.3 V andcommunicate with the microcontroller (14) via a common I²C bus.

In one embodiment, the temperature sensor (18) and the humidity sensor(20) are contained within one and the same sensing means; i.e. acombined sensor as depicted in FIG. 4 . In a specific embodiment, thecombined sensor is a digital sensor SHT21D (version 3) as supplied bySensirion which allows sampling frequencies up to 2 Hz with 12-bitmeasurement resolution.

In one embodiment, the atmospheric pressure sensor (19) is selected fromany sensor capable of measuring pressures in at least the range of about800 hPa to about 1100 hPa, or about 0.8 bar to about 1.1 bar; preferablysensors which are especially designed for mobile applications, such aspiezo-resistive pressure sensors. In a specific embodiment, theatmospheric pressure sensor (19) is a digital BMP280 sensor as suppliedby Bosch.

The positioning of the three environmental sensors (18, 19, 20) on themain board (27) is depicted in FIG. 4 . These environmental sensors (18,19, 20) may be used e.g. for the BTPS conversion of FVC measurements(BTPS: body temperature pressure saturated); i.e. the vital capacity atmaximally forced expiratory effort, expressed in litres at bodytemperature and ambient pressure saturated with water vapour, asrequired by the ATS standards of spirometry in order to allow forcomparability across different temperatures, pressures and humidityconditions; i.e. a standardisation of environmental conditions (see e.g.“Standardisation of spirometry”; Eur Respir J 2005; 26: 319-338).

In one embodiment, the microcontroller (14) is provided in the form of aso-called System-on-Chip (SoC) unit on a printed circuit board (PCB) asdepicted in FIG. 4 , also referred to as the main board (27). In aspecific embodiment, the microcontroller (14) is a nRF51822-QFAC (rev.3) SoC-unit as obtainable from Nordic Semiconductor and supplied with anARM Cortex-MO core which comprising a BLE radio module, a built-in 256kB flash memory and 32 kB RAM.

In one embodiment, the spirometer (1) further comprises a communicationmeans, preferably a wireless communication means, and more preferably aradio communication means (21) in order to connect the spirometer (1) toa user's personal computer and/or smartphone or any other computing unitwhich is adapted to collect, store, analyse, exchange and/or displaydata. The communication means is employed for the exchange of datarelated to the fluid flow generated by the spirometer (1), preferably bythe microcontroller (14) of the spirometer (1).

The wireless or in particular radio connection can be operative duringthe measurements, thereby allowing real time display of the measureddate. Alternatively, the spirometer (1) may be connected to the user'spersonal computer and/or his smartphone at a later time point totransfer, or copy, any measured and stored data from the spirometer (1)to the computer and/or smartphone. In a specific embodiment, the radiocommunication means (21) is a Bluetooth connectivity (21.1), e.g. aBluetooth 4.0 connectivity. In a further specific embodiment, the radiocommunication means (21) is a so-called Near Field Communication (NFC)means (21.2) or a Wireless Local Area Network (WLAN) means (21.3).Optionally, different types of radio communication means (21) may becombined in a device, e.g. a Bluetooth connectivity (21.1) together withan NFC means (21.2), as depicted on the main board (27) of FIG. 4 .

Measured parameters are digitalized and then wirelessly transmitted tothe user's personal computer and/or smartphone or any other computingunit which is adapted to collect, store, analyse, exchange and/ordisplay data, optionally via one or more remote data servers, alsocalled ‘cloud’. With regard to the cloud it should be understood, thatunlike other prior art devices, the spirometer (1) of the invention mayalso use a cloud, but does not require it for the device to be operable,to perform the measurement(s) and/or to obtain the result; all computingis done locally on the smartphone.

Further alternatively, or in addition to the radio communication means(21, 21.1, 21.2, 21.3), the spirometer (1) may further comprise a cablecommunication means (22) via a serial bus, such as a USB connection(22.1).

Both these communication means (wireless or using a cable connection)may further be employed for firmware updates.

In one embodiment, the spirometer (1) further comprises a RAM(random-access memory) and a flash memory in order to store measureddata.

As mentioned, the spirometer (1) may be connected to a user's personalcomputer and/or his smartphone, for analysis, visualisation and alsostorage of the measured spirometry data; preferably via a dedicatedspirometer application (‘app’) using a proprietary and predictivemedical algorithm; or as an ‘add-on’ integrated in other existinghealthcare apps available for iOS or android phones, such as GoogleFit,HealthKit, CareKit or the like (i.e. apps intended as personal andcentral data collection points for connected third-party electronicaccessories for medical and general fitness purposes, where users cane.g. create a medical ID with important medical details).

The dedicated proprietary app is employed to receive signals from thespirometer (1), measure and analyse results in real-time, display theappropriate parameters, store past results, provide diagnostic support,generate printabe files (e.g. PDF) for keeping a paper/computer formatlog, and optionally to send results to physicians. With the help of theportable electronic spirometer (1) and the related app, users can thustrack their personal respiratory parameters, as well as theresponsiveness to and adequacy of medication, in a far more close-meshedmanner than achievable in e.g. hospital settings.

In one embodiment, the collected data (up to 1,000,000 results) from thespirometer (1) are stored in the form of a logged history in the local,internal database of the app such that the data are readily availablefor the user even when he/she is offline. In case a user uninstalls theapplication, the database is also removed; however, Android's backup andiOS's CloudKit services allows users to copy persistent application datato remote cloud storage in order to provide a restore point for theapplication data and settings. When performing a factory reset orconverting to a new device, the system automatically restores backupdata when the app is re-installed, such that users don't need toreproduce their previous data or settings. Alternatively, or in additionto the local storage, cloud storage may be provided as an ‘opt-in’option for the user.

Optionally, the data measured and collected with the spirometer (1) mayfurther be combined with geographical data and data of multiple usersthen analysed collectively on a remote server in order to create maps ofspecific changes in conditions in a given area and time for e.g.asthmatic users or allergy sufferers. The data collected via suchgeolocation provides a framework for building analytical knowledge,correlating data to a certain area, and—where considered expedient—forproviding this knowledge to users and/or doctors in a given area, e.g.in the form of alerts on upcoming acute exacerbations and/or increasedallergy risks sent to their personal computers and/or smartphones. Thisoptional functionality will be provided for and to users in ananonymised fashion.

The spirometer (1) may further provide motivational messages to users inorder to coach them for self-management. It can also provide instantfeedback to the user while performing the spirometry measurement (e.g.audible or visual) which allows instructing and/or prompting a user toconduct a desired spirometric breath manoeuvre, such as rapidly exhalingat the right moment. This is believed to be unique for spirometers asother marketed spirometers do not do coach users on how to correctlyperform spirometry during the actual measurement, or breath manoeuvre,and/or what to improve in the next manoeuvre. This feedback and/ormotivational means facilitates in particular unsupervised use.

In addition, based on data mining and machine learning algorithmscomprised in the dedicated app, the spirometer (1) can identify clinicaland also environmental patterns (such as temperature, pressure andambient air humidity) that may be associated with e.g. an upcomingasthma attack and/or a disease progression in a predictive manner.Ultimately, users are thus enabled to eliminate or at least reducesevere hospitalizations due to acute and chronic exacerbations. However,as mentioned, the examination of respiratory parameters may also behelpful for athletes monitoring their training progress or for smokersmonitoring the benefits of smoking cessation.

In one embodiment, the spirometer (1) is operated with a long-lifebattery, such as a lithium-ion polymer (LiPo) battery or a lithium-ion(LiOn) battery. LiPo batteries offer high capacity compared to theirsmall size, and high-speed charging. In a specific embodiment, thebattery is a (re)chargeable 3.7V/300 mAh LiPo battery; for instance, anLP-402933-IS-3 battery featuring a built-in NTC 10 kohm thermistor and atransistor protection against overloading. A low-dropout (LDO) typevoltage stabiliser then supplies continuous current of 150 mA and a DCoutput voltage of 3.3 V when the spirometer (1) is switched on, forinstance to the microcontroller (14) and all sensors (13, 15-20). In aspecific embodiment, the voltage stabiliser is a TPS706 unit as suppliedby Texas Instruments. In addition, a voltage divider may be employed ifthe voltage directed to certain components of the spirometer (1) cannotexceed specific values; e.g. the voltage sampled by the microcontroller(14) not exceeding 1.2 V.

In one embodiment, the battery is charged via an inductive NFC chargingsystem and/or via a USB or mini-USB connector (22.1). In a specificembodiment, the basic component of the wireless charging module is a 5 Wunit (BQ51050B) as supplied by Texas Instruments, charging to themaximum voltage of 4.2 V. A reception coil (Wurth Elektronik coil760308103205) is connected to the unit with inductiveness of 11 μH. Theunit comprises a LiPo and LiOn battery charger with the function ofmonitoring temperature using an NTC thermistor (10 kohm). It alsoprovides the possibility of selecting a priority for the source ofcharging; for example, if USB charging is available via a connectedmini-USB port, the charging unit will stop wireless charging and switchto USB-charging. In a further specific embodiment, the basic componentfor the charging module is a BQ24040—unit as supplied by TexasInstruments, a LiPo and LiOn battery charger charging to the voltage of4.2 V. Maximum charging current is 800 mA, and maximum initial chargingby default amounts to 300 mA for devices with a 300 mAh battery, such asthe battery used in one embodiment of the spirometer (1).

The module which is responsible for detecting the charging source (e.g.wireless vs. USB) also performs the task of automatically starting thespirometer (1) during charging, as is necessary in order to inform theuser about the charging status by means of the LEDs (23.1); i.e. theuser does not have to start the spirometer (1) manually via ON/OFFbutton (25) in order to see the charging status. The microcontroller(14) uses the module to check the charging source and status, and thisinformation may also be provided to the user via the app. After chargingis completed, the device will be switched off automatically.

In one embodiment, the spirometer's (1) main body (9) is furtherequipped with optical (23) and/or acoustical (24) signalling meansproviding use-related information such as ON/OFF-status, battery statusand the like to the user. In a specific embodiment, the spirometer's (1)main body (9) is fitted with light emitting diodes (LEDs), for instancea set of blue LEDs (23.1) arranged at the top of the main body (9) asdepicted in FIG. 2 . The LEDs display specific status information, suchas device start-up, data transfer, low battery (e.g. all diodesflashing) or battery charging status (e.g. diodes illuminatingsubsequently).

In a more specific embodiment, the direct control of these LEDs isprovided by a TLC59108 unit. Each diode consumes only about 5 mA ofcurrent (depending on the light intensity) while the microcontroller(14) is able to supply a maximum of about 120 mA. The microcontroller(14) also enables to set the brightness of illumination using a built-inPWM module (pulse-width modulation), as well as to set the mode of diodeflashing with particular frequency and duration of illuminationon/off-time.

In one embodiment, the spirometer (1) exhibits a mean energyconsumption, or current consumption, during its operation that is nothigher than about 90 mA in total. Preferably, the mean energyconsumption does not exceed about 50 mA, even with all light emittingdiodes (LEDs) being illuminated. On average, the spirometer (1) equippedwith a freshly charged 300 mAh battery is operable for about 120 days instand-by mode, for about 56 days for single users and for about 5.6 dayswhen used for multiple patients in e.g. a doctor's office. The timeestimated for continuous, uninterrupted operation on one battery chargeis about 6 h. In other words, the inventive spirometer (1) is not onlyallowing for spirometric measurements at a remarkably high precision butis highly energy-efficient at the same time, thereby reducing the needfor expensive and heavy energy sources.

The spirometer's (1) main components which get in contact with theuser's skin, namely the tubular mouthpiece (2) and the main body (9),may be prepared from any biocompatible material, including biocompatiblepolymers. In one embodiment, biocompatible Polyjet photopolymer (MED610)is employed, a rigid medical material suited for prolonged skin contactof more than 30 days and short-term mucosal membrane contact of up to 24hours, but also suited for rapid prototyping. MED610 features highdimensional stability and colorless transparency. Also polycarbonate-ISO(PC-ISO) may be employed; a high strength thermoplastic material whichin its pure form is biocompatible and sterilizable by gamma irradiationor ethylene oxide (sterilization method ETO). PC-ISO is commonly usedfor packaging medicines and in the manufacture of medical devices.

As mentioned earlier, the front end of the tubular mouthpiece, i.e. theend comprising the proximal opening may optionally be configured as adetachable part of the tubular mouthpiece, thereby allowing to removethis front end portion of the mouthpiece; for instance, to clean it, orto discard and replace it, after contact with a user's lips and/ortongue. In case of such disposable front end portions (or otherdisposable parts as needed in multi-patient settings), the materials mayalso include more simple biocompatible materials such as cardboard.Alternatively, or in addition, the detachable front end portion of themouthpiece may be equipped with one or more filters to remove airborneparticles, saliva droplets and/or bacteria; thereby further reducing therisk of contaminating the sensitive MEMS-based thermal fluid flow sensor(13, 13.1, 13.2). Such filter-mouthpieces are available at low cost andthus may be replaced for each patient in multi-patient settings.

Further optionally the spirometer may be provided to the user togetherwith a nose-clip, such as to allow the user to block the nose whileperforming spirometric measurements. In one embodiment, the nose-clipand the spirometer are provided as a kit, optionally further comprisingreadable instructions on the correct use of the spirometer and/or thenose-clip.

In a second aspect, the invention provides a method for measuring ahealth parameter of a human subject selected from

a) a forced vital capacity (FVC),b) a forced expiratory volume (FEV) such as the forced expiratory volumein 1 second (FEV1),c) a peak expiratory flow (PEF)d) a forced expiratory flow (FEF) such as the forced expiratory flow at25%-75% of FVC (FEF25-75),e) a maximum voluntary ventilation (MVV),f) a mean expiratory flow,g) a slow vital capacity (SVC),h) a functional residual capacity (FRC),i) an expiratory reserve volume (ERV),j) a maximum speed of expiration,k) a forced inspiratory volume (FIV) such as the forced inspiratoryvolume in 1 second (FIV1),l) a forced inspiratory vital capacity (FIVC),m) a peak inspiratory flow (PIF),or any combination of these (e.g. an inspiratory Tiffeneau value:FIV1/FIVC), the method comprising a step of the human subject performinga breathing manoeuvre through the portable electronic spirometer (1) asdescribed above. The actual breathing manoeuvres are the same asperformed with prior art spirometers; the specifics will depend on theactual lung function parameter to be determined. Examples may be foundin the “Standardisation of spirometry” e.g. as pulished e.g. by theAmerican Thoracic Society (ATS) or the European Respiratory Sociuety(ERS) (see Eur Respir J 2005; 26: 319-338) or the ISO 26782:2009(specifying requirements for spirometers intended for the assessment ofpulmonary function in humans weighing more than 10 kg).

Beyond full spirometry, the spirometer (1) offers further potentialapplications, or uses, in various clinical scenarios. For instance, thespirometer (1) may be used for the differential diagnosis of dyspnoea;i.e. the device allows differentiating between cardiac vs. respiratorydyspnoea. When patients are admitted to emergency departments due tochest pain and dyspnoea, this is commonly caused by either coronaryinsufficiency (ischemia), heart failure (lung congestion) or bronchialobstruction (COPD). Commonly, a differential diagnosis is hindered bythe significant overlap of about 30% of ischemic heart disease (coronaryartery disease) patients and COPD patients. The spirometer (1) allows tounderstand if there is a significant obstruction, in which case thespirometric parameters would not be ok. Hence, if the spirometricparameters are ok, while the cardiac parameters are not, the chest painand further symptoms are most likely of a cardiac origin, while in thevice versa case, the symptoms are most likely caused bronchially. Ifboth, the respiratory and the cardiac parameters are not ok, the chestpain and dyspnea are caused by a combination of either coronaryinsufficiency (ischemia), heart failure (lung congestion) or bronchialobstruction (COPD).

In that aspect, it should be understood that this type of differentialdiagnosis would be possible with prior art devices, too; however, thedesktop spirometers as commonly found in hospitals are usually ratherlarge and require longer set-up times. The small hand-held spirometer(1) in contrast is far more practical and requires shorter set-up times,rendering it more suitable for use in emergency and/or intensive careunits.

Furthermore, the spirometer (1) may be used in hospitals duringpre-extubation assessment of respiratory patients which is one crucialelement to prevent failed extubations. The spirometer (1) may be used todetermine the efficacy of spontaneous breathing of an intubated patientby either applying the flow sensor (13, 13.1, 13.2) directly on theintubation tube and/or by coupling the spirometer (1) with theintubation tube, such as to measure the fluid flow caused by spontaneousbreathing while the ventilator is switched off.

Also, evaluation of cardiac arrest patient requires assessment of theelectrical activity as well as the haemodynamic function of the heart,the latter usually being evaluated using pulse. However, in patientswith peripheral artery disease and/or those with severe peripheraloedema it may be difficult to feel the pulse despite good haemodynamicfunction of the heart. The spirometer (1) allows to indirectly evaluatethe contractions of the heart by sensing the very discreet movements ofair in the lungs and trachea which is caused by the heart beats.

In a third aspect, the invention provides a system comprising:

-   -   the portable electronic spirometer (1) according to the first        aspect of the invention, and    -   a first air quality measurement device comprising communication        means adapted for data exchange with the portable electronic        spirometer (1) and/or with a separate computing unit, and        equipped with one or more air quality sensors, preferably        selected from the group consisting of humidity sensors,        temperature sensors, atmospheric pressure sensors, MOS-type gas        sensors (metal-oxide-semiconductor), airborne-particles sensors,        pollen sensors, ozone (O₃) sensors, nitrogen dioxide (NO₂)        sensors, sulfur dioxide (SO₂) sensors and carbon monoxide (CO)        sensors, for determining determine the air quality at the        location of the first air quality measurement device, and        optionally    -   a separate computing unit adapted to collect and analyse at        least the data obtained from the spirometer (1) according to the        first aspect of the invention and from the first air quality        measurement device.

Air pollution is known to be linked to a decrease in lung function inhealthy adults and children, and to adversely impact different acute andchronic pulmonary diseases, such as asthma, chronic obstructivepulmonary disease (COPD), bronchitis and cystic fibrosis (CF). Airpollution can trigger cellular responses in the lung, resulting incytotoxicity, inflammation, and mutagenesis. Bronchial epithelial cellsfrom patients suffering from pulmonary diseases are highly sensitive toairborne particulate matter-induced oxidative stress and apoptosis at amuch lower dose than healthy bronchial cells. Hence, an intense responseto the oxidative stress induced by air pollution remains the base fordisease progression and exacerbations. This pathomechanism was confirmedin observational studies which showed that the annual average levels ofair pollution exposure were associated with lung function decrease andan increased likelihood of exacerbation. Pulmonary exacerbationscontribute significantly to the burden of disease, with a negativeimpact on lung function, quality of life, health system costs.

Especially, particulate matter (PM), pollen, ozone (O₃), nitrogendioxide (NO₂), sulfur dioxide (SO₂) and carbon monoxide (CO) have beenidentified as key pollutants impairing health. For instance, there is aclose quantitative relationship between increased mortality or morbidity(both daily and over time) and the exposure to high concentrations ofinhalable coarse particles (2.5-10 μm; PM10), and inhalable fineparticles (≤2.5 μm; PM2.5). In fact, PM10 and PM2.5 pollution havehealth impacts even at very low concentrations; in fact, no thresholdhas been identified below which no health damage is observed. Therefore,guidelines such as by the World Health Organization (WHO) aim to achievethe lowest possible PM-concentration and advise annual means of max. 10μg/m³ (PM2.5) or 20 μg/m³ (PM10), and 24-hour means of max. 25 μg/m³(PM2.5) or 50 μg/m³ (PM10).

Also, excessive ozone (O₃) in the air can have a marked effect on humanhealth. It can cause breathing problems, trigger asthma, reduce lungfunction and cause lung diseases. In Europe, it is currently one of theair pollutants of most concern. Several European studies have reportedthat the daily mortality rises by 0.3% and that for heart diseases by0.4%, per 10 μg/m³ increase in ozone exposure. An 8-hour mean of max.100 μg/m³ is advised by the guidelines.

Epidemiological studies have shown that symptoms of bronchitis inasthmatic children increased in association with long-term exposure tonitrogen dioxide (NO₂). At short-term concentrations exceeding 200μg/m³, it is even toxic, causing significant inflammation of theairways. A 1-hour mean of max. 200 μg/m³ is advised by the guidelines.

Sulfur dioxide (SO₂) can affect the respiratory system and lungfunction, causing inflammation of the respiratory tract and resulting incoughing, increased mucus secretion, aggravation of asthma and chronicbronchitis and an increased risk of respiratory tract infections.Studies indicate that exposure periods as short as 10 minutes alreadyincrease the proportion of asthma patients experiencing changes inpulmonary function and respiratory symptoms. Asthmatic subjectsexercising in SO₂-polluted air develop bronchoconstriction withinminutes, even at levels as low as 0.25 ppm. Lung function parameterssuch as FEV1 were decreased in response to exposure to only 0.4 to 1.0ppm SO₂. Furthermore, hospital admissions due to cardiac disease andmortality are increased on days with SO₂ levels above the recommended24-hour mean of max. 20 μg/m3 or the recommended 10-minute mean of max.500 μg/m³.

Carbon monoxide (CO) remains the second most strongly correlated airpollutant causing asthma hospital admissions.

The first air quality measurement device is used to generate datarelated to the air quality (or lack thereof), for instance, the natureand/or the extent of air pollutants (ozone, pollen, particulate matter,etc.) present at any given time at the location of the first air qualitymeasurement device, such as inside the home of the subject using thespirometer (1).

For this purpose, the first air quality measurement device comprises oneor more sensors selected from the group consisting of humidity sensors,temperature sensors, atmospheric pressure sensors, MOS-type gas sensors(metal-oxide-semiconductor), airborne-particles sensors, pollen sensors,ozone (O₃) sensors, nitrogen dioxide (NO₂) sensors, sulfur dioxide (SO₂)sensors and carbon monoxide (CO) sensors. These sensors may be providedseparately (in other words, one sensor for each measurand).Alternatively, the sensors may be combined such as to use one sensor fora plurality of measurands. Exemplary and non-limiting embodiments ofthese sensors will be described below.

In one embodiment, the humidity sensor, the temperature sensor and thepressure sensor may be provided in combined form. In a specificembodiment, the sensor is a Bosch® BME280 sensor, a small (2.5×2.5×0.93mm), high performance combined, digital humidity—, pressure, —andtemperature sensor with a low power consumption. The humidity sensorprovides an extremely fast response time and high overall accuracy overa wide temperature range. The pressure sensor is an absolute barometricpressure sensor with extremely high accuracy and resolution anddrastically lower noise. The integrated temperature sensor has beenoptimized for lowest noise and highest resolution. Its output is usedfor temperature compensation of the pressure and humidity sensors andcan also be used for estimation of the ambient temperature.

In one embodiment, the MOS-type gas sensor is a FIGARO® TGS8100 airquality sensor comprising a sensing chip with a metal-oxidesemiconductor (MOS) layer and an integrated heater on a siliconsubstrate. The sensor is housed in a standard surface-mount ceramicpackage and requires a heater power consumption of only 15 mW. In thepresence of detectable gases (such as hydrogen, ethanol, carbon monoxide(CO), isobutane, methane, cigarette smoke, kitchen odors, or the like),the sensor conductivity increases depending on gas concentration in theair. A simple electrical circuit can convert the change in conductivityto an output signal which corresponds to the gas concentration.

In one embodiment, the airborne-particles sensor is a Sharp®GP2Y1030AU0F, a high sensitivity airborne-particles sensor (also calleddust sensor) operating with a built-in microcomputer and an opticalsensing system that can detect e.g. particulate matter like PM2.5 andPM10. An infrared emitting diode (IRED) and a phototransistor arediagonally arranged in the sensor to detect the light reflected byairborne particles such as dust and/or cigarette smoke with the sensorbeing able to distinguish these two by a pulsed pattern of outputvoltage.

In one embodiment, the ozone (O₃) sensor is a small-sized (15×15×3 mm),printed ozone sensor, such as the 35P-O3-20 sensor by SPEC sensors.

In one embodiment, the nitrogen dioxide (NO₂) sensor is anelectrochemical sensor, such as the Figfaro FECS42-20 sensor.

In one embodiment, the sulfur dioxide (SO₂) sensor is an amperometricgas sensor, also provided by SPEC sensors; i.e. an electrochemicalsensor which generates a current at a working (or sensing) electrodethat is proportional to the volumetric fraction of the SO₂ gas. Besidesthe working (or sensing) electrode and its counter-electrode, the sensorcomprises a reference electrode to improve stability, signal-to-noiseratio, and response time.

In one of the preferred embodiments, the first air quality measurementdevice is not only responsible for generating data related to the airquality via its inbuilt sensors but further serves as a charging dock,or docking station, for at least the portable electronic spirometer (1),preferably a Near Field Communication (NFC) charging dock. Like this,the spirometer (1) only needs to be placed on top of the first airquality measurement device to recharge; for instance, over night.

Besides the sensors for determining air quality, the first air qualitymeasurement device further comprises a microcontroller and acommunication means, preferably a wireless communication means, andfurther preferably a Bluetooth connectivity, such as Bluetooth 4.0. In aspecific embodiment, the microcontroller is a nRF51422-CEAA as producedby Nordic Semiconductor, comprising a 32-bit ARM® Cortex™ M0 centralprocessing unit (CPU) with 256 kB flash and 32 kB RAM as well as anembedded 2.4 GHz transceiver. The microcontroller allows for bothBluetooth® low energy (BLE; previously called Bluetooth Smart) and ANT™wireless connectivities. A ceramic antenna for Bluetooth 2.4 GHz is usedfor improved reception and more stable connection.

As mentioned, the separate computing unit is adapted to collect andanalyse at least the data obtained from the spirometer (1) and from thefirst air quality measurement device. The purpose of the separatecomputing unit is to allow for comparison and/or correlation of the dataobtained from the spirometer (1) with the data obtained from the firstair quality measurement device (and optionally further data), in orderto obtain a deeper insight into e.g. the pathogenesis of respiratorydiseases; for instance, to correlate days of poorer results inspirometric lung performance tests run by the spirometer (1) with theair quality data measured by the first air quality measurement device onsuch days.

For this purpose, the separate computing unit in one embodimentcomprises a communication means coupled with a microcontroller forperforming data collection and data analysis (e.g. a microcontroller inthe form of a so-called System-on-Chip (SoC) unit on a printed circuitboard (PCB)); and data storage means (e.g. a random-access memory (RAM)and/or a flash memory) in order to store collected and/or analysed dataobtained from at least the spirometer (1) and the first air qualitymeasurement device (hereafter shortly referred to as ‘spirometer data’and ‘first air quality data’, respectively), and optionally furtherdata.

Furthermore, the separate computing unit typically comprises aninterface that is adapted to communicate with a user of the inventivesystem (e.g. the user of the spirometer (1), his/her physician orcaretakers), and to provide information to the user on any of the‘spirometer data’ and ‘first air quality data’ as well as informationobtained from comparing and/or correlating the ‘spirometer data’ and‘first air quality data’. In one embodiment, this interface is a visualdisplay.

In one embodiment, the separate computing unit comprises a wirelesscommunication means, preferably a radio communication means; e.g. aBluetooth connectivity or a Near Field Communication (NFC) means.

In one embodiment, the separate computing unit is a personal computer(including laptops and handheld PCs) and/or smartphone.

In a further embodiment, the system may comprise two or mor separatecomputing units, optionally in the form of personal computers (includinglaptops and handheld PCs) and/or smartphones.

In one embodiment, the separate computing unit is furthercommunicatively coupled to one or more remote data servers. Said remoteservers may be employed to store and analyse the ‘spirometer data’ and‘first air quality data’, information obtained from comparing and/orcorrelating the ‘spirometer data’ and ‘first air quality data’, andoptionally further data.

In one of the preferred embodiments, a proprietary software application(‘app’) is provided on the separate computing unit and/or the remotedate servers for performing the comparison and/or correlation of atleast the ‘spirometer data’ and ‘first air quality data’. In a specificembodiment, the app may also be programmed to perform further tasks suchas displaying the ‘spirometer data’, the ‘first air quality data’ and/orinformation obtained from their comparison and/or correlation to a userof the inventive system (e.g. as graphical interpretations of the datavia interface(s) of the one or more computing units); monitoring saiddata and information as well as a user's medication over the course oftime; creating printable file formats of any data analysis results; sendreminders or warning notice to the user (e.g. related to medication timepoints, smog-warnings, etc.); and/or sharing information with healthcare providers such as physicians, care givers, health careorganisations and/or other users of the ‘app’ (optionally in anonymisedform).

Optionally, the system as described above further comprises a nose-clip,such as to allow the user to block the nose while performing spirometricmeasurements. Further optionally, the system further comprises readableinstructions on the correct use of the spirometer and/or the nose-clip.

In one embodiment, the system as described above further comprises asecond air quality measurement device adapted for data exchange with theportable electronic spirometer (1) and/or with a separate computingunit, and equipped with one or more air quality sensors, preferablyselected from the group consisting of humidity sensors, temperaturesensors, atmospheric pressure sensors, MOS-type gas sensors(metal-oxide-semiconductor), airborne-particles sensors, pollen sensors,ozone (O₃) sensors, nitrogen dioxide (NO₂) sensors, sulfur dioxide (SO₂)sensors and carbon monoxide (CO) sensors, in order to determine the airquality at the location of the second air quality measurement device.This second air quality measurement device may be used in addition tothe first air quality measurement device, or optionally instead of thefirst (e.g. when travelling). With respect to the selected sensors, thesame provisions may apply as described for the first air qualitymeasurement device described above.

Unlike the first air quality measurement device which is typically morestationary (for instance, set up in the home of the user), the secondair quality measurement device may be more easily portable in that it iseven smaller and more compact than the first device. For instance, thesecond air quality measurement device may have a size which allows e.g.attachment to a keychain whereas the first air quality measurementdevice may have a size and shape resembling an external hard drive (e.g.about 7-17 cm long and about 4-8 cm wide). Like this, the second airquality measurement device may e.g. be used when travelling, or thedevice may be used at work, in the car or any other place of interest,where the subject using the spirometer (1) wants to determine the airquality. It is also possible to place the second air quality measurementdevice outside.

In one embodiment, the separate computing unit of the system asdescribed above also collects and analyses the data obtained from thesecond air quality measurement device. In this case, the data obtainedfrom the second air quality measurement device (shortly, the ‘second airquality data’) may be treated in the same way as the data obtained fromthe first device; e.g. compared and/or correlated with the ‘spirometerdata’.

In one embodiment, the separate computing unit further allows for thegeolocalisation of at least the air quality data obtained from the firstair quality measurement device, and optionally of the air quality dataobtained from the second air quality measurement device. Thegeolocalisation functionality may be provided for all users, preferablyin anonymous form such as to retain the privacy of each user. Based onthis functionality, the inventive system may be able to, for instance,provide warnings to a user (e.g. on smog, pollen and/or other allergenswhich may impact their lung functions and/or respiratory health), and/orto create geographic maps of all users along with the changes in theirrespective lung function and/or respiratory health condition at anygiven time. The data collected through geolocalisation may thus providea framework for building an even further analytical knowledge of thedata provided, e.g. the correlation to a certain area, to specificweather phenomena, etc.

This means, by using the system according to the third aspect of theinvention, the method according to the second aspect of the inventionmay be complemented with additional data such as data related to the airquality (pollutants, ozone, etc.) and/or geolocation data, therebyallowing to correlate the health parameter of the human subject (such asFVC, FEV or PEF) with these additional data.

In other words, in a fourth aspect the invention provides a method formeasuring one or more health parameters of a human subject selected from(a) a forced vital capacity (FVC), (b) a forced expiratory volume (FEV)such as the forced expiratory volume in 1 second (FEV1), (c) a peakexpiratory flow (PEF), (d) a forced expiratory flow (FEF), such as theforced expiratory flow at 25%-75% of the FVC (FEF25-75), (e) a maximumvoluntary ventilation (MVV), (f) a mean expiratory flow, (g) a slowvital capacity (SVC), (h) a functional residual capacity (FRC), (i) anexpiratory reserve volume (ERV), (j) a maximum speed of expiration, (k)a forced inspiratory volume (FIV) such as the forced inspiratory volumein 1 second (FIV1), (l) a forced inspiratory vital capacity (FIVC), (m)a peak inspiratory flow (PIF), or any combination of these (e.g. aninspiratory Tiffeneau value: FIV1/FIVC),

the method comprising a step of the human subject performing a breathingmanoeuvre through the spirometer (1) as described above as the firstaspect of the invention; wherein the one or more health parameters arecorrelated with air quality data, and optionally geolocalisation data,derived from the system as described above as the third aspect of theinvention.

1. A portable electronic spirometer (1) comprising: (a) a tubularmouthpiece (2) with a proximal opening (3) for insertion into the mouthof a user, a distal opening (4), a main fluid channel (5) extendingbetween the proximal opening (3) and the distal opening (4), a firstlateral opening (6), a second lateral opening (7) positioned at alongitudinal distance to the first lateral opening (6), and a flowrestrictor (8) positioned in the main fluid channel (5) between thefirst and the second lateral opening (6 and 7); and (b) a main body (9)with a first fluid opening (10) connectible with the first lateralopening (6) of the mouthpiece (2), a second fluid opening (11)connectible with the second lateral opening (7) of the mouthpiece (2), abypass fluid channel (12) extending between the first and the secondfluid opening (10 and 11), a MEMS-based thermal fluid flow sensor (13)positioned at the bypass fluid channel (12) for generating a signal inresponse to the fluid flow in the bypass fluid channel (12), and amicrocontroller (14) connected with the fluid flow sensor (13) forcalculating the fluid flow from the signal generated by the flow sensor(13). 2-15. (canceled)
 16. A method for measuring a health parameter ofa human subject selected from: (c) a forced vital capacity, (d) a forcedexpiratory volume, (e) a peak expiratory flow, (f) a forced expiratoryflow (FEF), (g) a maximum voluntary ventilation (MVV), (h) a meanexpiratory flow, (i) a slow vital capacity (SVC), (j) a functionalresidual capacity (FRC), (k) an expiratory reserve volume (ERV), (l) amaximum speed of expiration, (m) a forced inspiratory volume (FIV), (n)a forced inspiratory vital capacity (FIVC), (o) a peak inspiratory flow(PIF), or any combination of these, the method comprising a step of thehuman subject performing a breathing manoeuvre through the spirometer(1) of claim
 1. 17. A system comprising: the portable electronicspirometer (1) of claim 1, and a first air quality measurement devicecomprising communication means adapted for data exchange with theportable electronic spirometer (1) and/or with a separate computingunit, and equipped with one or more air quality sensors, preferablyselected from the group consisting of humidity sensors, temperaturesensors, atmospheric pressure sensors, MOS-type gas sensors(metal-oxide-semiconductor), airborne-particles sensors, pollen sensors,ozone (O₃) sensors, nitrogen dioxide (NO₂) sensors, sulfur dioxide (SO₂)sensors and carbon monoxide (CO) sensors, for determining determine theair quality at the location of the first air quality measurement device,and optionally a separate computing unit adapted to collect and analyseat least the data obtained from the spirometer (1) of claim 1 and fromthe first air quality measurement device. 18-23. (canceled)
 24. A methodfor measuring one or more health parameters of a human subject selectedfrom a) a forced vital capacity (FVC), b) a forced expiratory volume(FEV), c) a peak expiratory flow (PEF), d) a forced expiratory flow(FEF), e) a maximum voluntary ventilation (MVV), f) a mean expiratoryflow, g) a slow vital capacity (SVC), h) a functional residual capacity(FRC), i) an expiratory reserve volume (ERV), j) a maximum speed ofexpiration, k) a forced inspiratory volume (FIV), l) a forcedinspiratory vital capacity (FIVC), m) a peak inspiratory flow (PIF), orany combination of these, the method comprising a step of the humansubject performing a breathing manoeuvre through the spirometer (1) ofclaim 1; wherein the one or more health parameters are correlated withair quality data, and optionally geolocalisation data, derived from thesystem of claim 1.